Transfer of H1 to another Employee

[Dhruva]

Hi, I am out of job from 3/04. I have the paystub having the Pay date as 03/16. I was being paid for every two weeks. Now I want to change my employer. Considering my pay date(3/16 and pay period is ending 03/04) can some one tell me By what date I should apply for H1 transfer.

Your help would be highly appreciated.