Can you pay a security deposit then move in and prorate later in the month ie Pay security deposit on the first to secure the home then move in on the middle of the month and pro rate?

NO. A security deposit is equal to one, one and a half or two months rent as regulated by your state Landlord Tenant Law, according to RentLaw.com .

It depends on the landlord. Most companies will be happy to do this for you. Know that it is illegal for landlords to charge "double rent" on an apartment (having two parties paying rent for the same unit).

Some landlords will try and pro-rate the last month rather than the first month. Be leery of this, but if you must accept it, get it in writing, make sure it's included in your lease agreement, and keep a copy in a place where you can find it.

You shouldn't have any problem doing what you're describing, as long as you stick to your move-in date. Landlords get nervous when people push moving in back more than a few days.