Usually, Saturday to Saturday.

Your best bet is to find a place you like first, then see what they say. What do you mean by start time? Check in time?

Roamsaround is correct, so traffic is interesting on Saturdays. Where are you coming from? Are you flying or driving?

Check-in time is usually between 3PM and 4PM on Saturday (depends on place) - very doubtful you could get occupant before that times as houses/condos have to be cleaned after old guests leave and before new ones arrive. Check out is before 11AM, also on Saturdays. It's hectic on Saturdays with people leaving in the morning and others arriving in the afternoon.

suewoo gives good advice, pick the place you want to stay than check with them for check-in times.

Friends who live on the island dread Saturdays in summer when all the "tourons" (that's tourists who drive like morons) are on island.

and if it is like other beaches, it is a total traffic jam trying to get to the real estate office.

driving in from east tn. may be picking up our son in atlanta. we're trying to plan a family get-together with the sons who live in different cities. but work schedules mean we need to think about what week, and thus what days of the week we talking about. ... we're initially thinking of getting a house and staying together. we can look at arriving other days of the week as well. i guess we were starting the time and then finding a place, rather than vice versa.

I don't think there will be any beach places in the summer that will rent other than Saturday to saturday or sunday to sunday. I suppose you might find a VRBO that would. Since you seem unfamiliar with Hilton Head, is there a particular draw there?

We have stayed in both Sat to Sat and Sun to Sun. We usually try to arrive pretty early and have a nice lunch upon arrival - that helps us miss a lot of the traffic coming in and is a nice way to start a vacation. We also use the toll road on the island. We have used many VRBO properties and other rental programs on the island and have never been disappointed. The bike trails on the island are great - I would make sure and check if any of the rentals offer bikes with the rates. It is a nice family vacation place for those who want lots of variety in choice (great golf, biking, horseback riding, restaurants, and outlet shopping). Have a great trip!

My strategy is to reserve two rooms at a hotel which can be canceled. I use them as my backup plan. Then I start contacting owners on VRBO at units I want to stay at in April. I say that I'm local (SC) and I can travel without airline reservations. I ask if they have a vacancy in their summer schedule I would love to split a week. (We prefer to stay either three or four days.) I have always been successful. The owners are greatful to get some rent during a week they thought they couldn't fill. I don't have to pay for a whole week, but I do have to pay the cleaning fee.

Yes the traffic during the Saturday checkin rush is awful. Leaving on Sunday is bad also.