The college will will usually give you a deadline for accepting offers of admission. Typically there is a deadline of May 1 for regular admissions for the Fall semester.
If the college has rolling admissions instead of regular admissions, then they might provide a "rolling" deadline for acceptance (within X number of days of the offer).
In many cases, especially in rolling admissions, colleges may provide financial aid, scholarships or housing on a "first come, first served" basis, so accepting the offer and paying your deposit as early as possible would be beneficial. If the college is your first choice, there's really no reason not to pay the deposit as early as possible, at least as soon as you receive your financial aid offer and know you can afford to go there.
Of course, if another college is your first choice, then you don't want to pay multiple deposits (and have to write multiple "I have changed my plans and will not be attending your fine institution" letters). That said, you don't want to gamble on getting accepted to your dream school, get rejected, and find that you've lost out on housing and scholarship opportunities, or even missed the deposit deadline, at your second choice.
So keep an eye out for the deadlines, and pay your deposit at (at least) one college you wouldn't mind going to while you wait for other offers to come through.