Buy condo with existing tenants

[Prash Sun]

[This is my first ppost but I have been lurking here consuming as much info as I can.]

I am planning to buy a condo in a high-rise building in NJ. The unit has a tentant whose lease expires end-of-June. I m getting a loan to buy it as primary residence and live there fora  year before converting to a rental unit. Now, this is my first home and I don;t want to handle the eviction and all that sorts. 

How do you draft the contract such that the tenants move out before the closing. Let's say the owner gave them $$ to vacate in 60days(end of March). And my closing date is April 1st. How do I make sure a smooth process? Any advice on negotiating terms with the seller? Anybody wen thru something similar? What did you do? 

Thanks!