Buy Replacement Property b4 Sell Old Property (Reverse Exchange)?

[Neil G.]

Cousin in NY is selling investment/income property (detached 2 fam) but in the mean time, found a replacement investment property (detached 2 fam) wants to close on instead of having to wait on closing on the old property first.

Can 1031 does without having to move either property temporarily to a third party/entity temporarily or anything? 

Also, what is the time frame for closing on the 2 deals? Do they have to be within say, the same 180 days. Is there any 45-day limitation, if so, for what?