How many months of reserves do you have on hand? Whether it be for after closing, finishing renovation, or for turn-over on a rental? I'm sure it would be great to have a tenant lined up to move in right away, but...

I'm looking to purchase a multifamily Unit in the Southern California area.  How much  money should I have in reserves when purchasing a multiunit? What is a general good rule of thumb to go by? 

A property owner is looking to sell his property to me. he's retireing, I got all the numbers worked out, applied the 50% rule and get a cash flow of about 2700 a month.

I'm 23 years old and dont have cash reserves ...