But off hand I anticipate around 40k but I can be completely off.

If you are using a company that will only finance 80% or 90% of purchase then they will want to see that you have the money on hand to make the down payment plus all the costs.Just know that the reason they are looking for cash on hand is that they want you to succeed and know that there will be costs that will come about.

It takes first hand experience to get to these numbers as it can vary, again by location, amenities, etc...  

Can you cover the difference with cash on hand?

@Simon W. it appears on the right hand side of the screen usually!

I wouldn't sell any houses, it's not like getting that chunk of change today is do or die for you financially and you'll have a foreclosure or repo on your hands without the sale.

On the other hand, make sure you accept only reasonable requests from your tenants, because they will walk all over you if you say yes to everything.

The way the wholesaler works is you have to have a 10k non refundable earnest money check in hand if you want the deal, and there were 5 other groups of investors walking the home while we were there.

Given all these things, is it advisable for my father in law to not 'hand over the keys' until at least closer to the anticipated close of escrow in the case that it is 2-3 months out?

I sell a handful annually off the MLS and thats a solid price!