As soon as you have access to the funds, you have constructively received the income, and thus you will owe taxes on the money. If you just have a post dated check but no money as yet, you cannot be taxed on income you have not received.
Just beware it that it is not the widow of a former Nigerian Dictator wishing to rent out your illustrious home and is willing to send you 10 post dated checks for more than the amount owed.
She will probably offer to let you keep the 75%-90% of the check, but ask for the rest back because she will not need your place, and sorry for the inconvenience....
....and then you will find out her original check bounces.