Tenants say they will leave. ( I AM UNSURE) Please help!

[Jose Alonso]

Hey guys your input is greatly appreciated. So I closed on this Duplex in Miami on March 15, 2016. I gave the tenants a letter that they had to move by April 25th, giving them 41 days. Mind you on Feb 21st I also informed them that they had to move which they're response to me was "your not the owner yet". On March 15 they singed the letter saying they would move by April 25th. Now both tenants are assuring me not to worry that by May 1st they wont be in the property, they seem like honest people I want to believe them but I am scared. Giving my living situation I have to move by April 30th which if they don't leave would leave me no choice but to rent a hotel. In Miami eviction process takes 5 weeks, which first 2 weeks are like a warning process letting tenants know they have to move or will get evicted. It will cost me $400.00 to send the first part of the process to them gaining 2 weeks if they decide not to honor they're word. Should I send them the unlawful tenancy letter or just wait it out and see if they indeed leave on April 30th?.