How many months should I plan to pay for the full mortgage?

[Matthew Powers]

Hi everyone! I am currently 22 years old and I am planning on using my FHA loan to buy a multifamily home within the next few years. I am curious to know how much money, BESIDES the downpayment, I will need. My main questions would be, how long until I would find a renter/s? How many months should I plan to pay for the full mortgage before I start receiving rent money? Lets assume I will not have to make any major repairs before renting. Thanks for the help!