I'm wondering how many months of mortgage payments should I have in the bank to keep the house afloat until rented.

The typical acquisition profile is a luxury beach vacation rental in the $650-$850k range either with cash or 50%+ down payment from the sale of a property in another state.

Some tenants I have gone months without talking to and only talked to them because I haven't heard from them in a while (even though their payments come in electronically with no issue).

@Chris SeveneyExcellent point.The the new property's cash flow can make your car payment or use that cash to build up for the next property.

We are getting a VA loan as that's the lowest down payment.

I have the lease and can make a spreadsheet for payment stuff.

I have multiple properties with equity and cashflow I am looking to put a 2nd private mortgage on and I would pay 10% Interest only payments per month. 

The situation is the father/seller was previously renting out the house to his son until he stopped payment according to seller around August 2021.

I can afford a substantial amount for the monthly payments on the house.

My monthly HH income is 16k USD after tax.After looking at multiple properties and calculating the overall net income it is quite difficult to come to a net positive cashflow (taking into account Mortgage payment, HOA, property taxes, insurance, rental taxes).