I am planning a trip to NYC for June 13th-17th and want to see as many musicals as possible. I am wondering how far in advance I should be getting tickets. I don't particularly want to wait in line at TKTS for a potential deal, but at the same time don't want to pay full price if its not necessary. I also don't want to miss out on seeing a show because I waited too long. I was a little shocked to see prices for Book of Mormon and Lion King so high considering they are not necessarily new. Anyway advice to navigating this world would be helpful. I am interested in the following shows, in no particular order:
Lion King
Book of Mormon
Matilda
Newsies
Once

broadwaybox.com has discounts for Matilda, Newsies, and Once. The discounts posted now expire before the dates of your trip, but the dates continue to update as time passes. I don't think you'll find discounts anywhere for Lion King or Book of Mormon.

You should buy tickets now. It's likely already too late to get really good seats for Book of Mormon, but there is probably something still available. The rest should probably still be around, though you should certainly look at Broadwaybox.com for discounts. Newsies and Once are almost always discounted at 30% to 50%, and Lion King is almost never discounted. But Matilda is new, and you may be able to get tickets right now at a discount.

You won't find any discount offers for any show for June until, say, April at the earliest.
The Book of Mormon definitely will NOT be offering discount tickets for quite a long while. So, if you want to see that show, definitely follow Doug's advice and get the tickets now/ Similary, the chance for discount tickets for The Lion King are very slim. So, again, get those tickets now.
As for the other three, the chances for discount offers in a couple months are pretty good. So, wait on getting those.
In response to the OP's comment expressing surprise at the high price of long-running shows, the answer is simple: The high prices have everything to with demand, not longevity!

Thank you so much for this valuable information. Looks like Book of Mormon is out, and I will be getting Lion King Tickets soon. Then will wait and see what I can get for the others a little later at a discount.

Unless you have a particular reason for wanting to see The Lion King, I would drop it and focus on Book of Mormon. I loved The Lion King movie but I was disappointed by the performances of the musical. We saw the traveling Book of Mormon, which is really, really entertaining.

sburns, Can you give details regarding The Book of Mormon lottery? Sounds interesting.

Actually, it's better if you read about it yourself on the web site: http://tinyurl.com/43wg8ko