My concern then is if I ultimately cant get financing I don’t want to lose my deposit.

@Dwight Cook  first don't forget to have a estoppel before closing specifying what is rent/security deposit etc. for each unit.  

The seller is friends with the tenants, so no background check was done and no security deposit was collected.

. - Have enough (take home after tax pure cash flow) from my properties to match my current w2 net income ( which roughly 7500$ to $11000 monthly)- Not create a lifestyle where I am so immersed in my real estate investments that I cannot enjoy life.

Do i collect his deposit now and then offer the lease at the beginning of his tenancy? 

The buyer has five business days to deposit per our contract.

You may need a separate bank account to hold the security deposit, for example of the latter. 

In this market you are using the low money down strategy to get into hopefully a break even property, where you can start building large sums of "forced savings" while you are living there for cheaper than the average rents in the area, and then forced savings once you move out with the tenants putting that "forced savings" deposit into your property every month.  

Say you have matching linoleum and you can patch it on November 28, tell them you will be scheduling someone on or about December 27th after Christmas as to not interrupt their plans.  

If rent is $2,000 a month, charge him first, last, and a double deposit.