Wow it's going to be really busy that day. Pack your patience. I know there are some really knowledgeable people on Trip Advisor.

Bring or rent a stroller. Go as soon as the park opens and grab a Fastpass for an adult ride (such as Star Tours, Space Mountain, etc). If you don't know abut the FastPass or the "Baby Switch" pass ask a Cast Member. There are also Single Rider Passes for several of the coasters, including Space Mountain, Big Thunder, these save time if only a few adults wish to go on the fast rides and don't care to sit together.

Be aware that the "dark rides" in Fantasyland can be scary for some 3 year olds. The Pirates of the Caribbean and Haunted Mansion are good rides for everyone to do together, I might start there (shouldn't be a long wait in the morning), then head to the Pooh ride which rarely has a line.

Check the height limits for rides
http://disneyland.disney.go.com/plan/guest-services/height-requirements/

Eat lunch at off=hours, make reservations if you want a sit down meal.

i agree with mlgb about "dark rides" (meaning those where the inside is dark). Our DD and my DH took our 3 yr old grandson and he was terrified of Mr. Toad's ride, didn't like the submarine, wouldn't go on the Peter Pan ride, but was ok with such things as Small World and the whirling Tea Cups.

There are MANY rides that a 3 year old is not allowed on - and as noted above, many that might well frighten him.

I would get a detailed map of the park and pick out those thins he CAN do - and then decide how to switch off - so the adults can each ride a couple of grown-up rides alone while the other parent does something with the child.

Also - don't expect a 3 year old to last the whole day - it simply isn't realistic.

My advice is skip the Dumbo ride! (We took our son the first time when he was 3, and spent at least 45 minutes in line for that 30-second ride).

My nephew, who was afraid of almost everything, loved Dumbo as well as the Casey Jr. train. He was one of those kids who loved trains and anything mechanical. All of the Fantasyland rides have ridiculous lines for 30 second (or so it seems) rides. Go as early as you can or during a parade, but just pick out a few that the kid may like.

This may not be what you want to hear . . . but I would not even consider it. Christmas is very VERY crowded at DL. Lines will be enormous. Fastpass is only offered for some rides.

I'd wait a couple of years and not go on a major holiday. Your child will be older, probably braver, and the whole family will have more fun.

I agree with JanisJ. Wait until he/ she is a little older, take them out of school and go on a Tuesday - Thursday.

Next to the 4th of July, Christmas Day is probably the busiest day at the parks. So, expect this. I agree with other posters, get there at rope drop (the moment they open....so get there 45 minutes early to park, get in line, etc.). Have one person go to the adult ride you want and snag a FP while the rest head directly to Fantasyland. If you want to do Dumbo, do that first. It is an incredibly slow loading ride which means that lines for it get crazy long very fast. Do as much as you can in Fantasyland as early as you can as the lines get long. Keep snagging FPs as soon as you are able to get on the adult rides you want.

Good luck!

IF you are sticking to this madness - some rides have single rider lines that are much quicker. Since one of you will have to stay w/ the 3 yo anyway - take advantage of the single lines. At least Indiana Jones and Splash Mountain have them - not sure of others.

IF you do go, good advice about getting to the rides in Fantasyland first thing. Go straight out the gate to Dumbo, the Teacups, Carousel, etc. these are the slow loading rides so the lines get very long very fast.

Some kids are scared of rides while other kids love them. My daughter loved all the rides, but would get upset if she wasn't tall enough for some of the bigger rides. I do think everyone should ride Dumbo once or twice in their life. I would do it the very first thing. I do agree that you shouldn't expect a child to last all day and getting there as early as possible before the park opens.

Or go late in the day when families with kids have left,

We're not early risers, so we went from about 1:00 to 10:00 the first time. My son slept through the Michael Jackson 3D thing, but was game for more when he woke up!

Please this is Christmas Day...the advice to go later will just lead to disaster!!!!

I agree w/ mlgb. Christmas is not a typical day at DL. Thousands of locals will be arriving later in the day - it is a Xmas tradition for lots of families.

If you go later in the day there is a possibility that park will be at full capacity and you will be turned away.

If you look at mice chat, allears, and other sights--it seems that Christmas Eve might be better, but I don't know. Personally, I would never consider going at a busy time. Even the slow times are busy to me.

I am not sure the OP is still with us but wanted to remind him or her that Disneyland has closed for capacity (meaning they sell no tickets and allow no one to enter the park) as early as 10 or 11am in recent years on Chrstmas Day. So, really, your best bet (your only bet unless you want to go late at night) is to get there before the park opens, have a touring plan and be ready to go at Rope Drop. Good luck!

We actually just returned from a day at Disneyland with our 19-month-old son. It was fantastic, even if he won't remember. I summed up our tips, post-visit, in a post: http://www.hitherandthither.net/2013/02/visiting-disneyland-with-a-toddler.html

alovesa: A HUGE difference between a Sunday in Feb and CHRISTMAS Day - which is what the OP asked about . . .