I would like to know when you don't have an agreement with landlord when your rent is due. When is it fair to consider that your rent is late. Isn;t they an alloted time.
If you have no written lease and no oral agreement which says exactly when you must pay your rent then your rent is due at the END of the rental period. So if you pay for one month at a time, your rent is due at the END of the month: this is "common law" and goes way back to feudal times. Most leases make you pay on the 1st day of the month. If you have no wriiten lease and no oral agreement to pay a late fee, your landlord cannot charge you a late fee no matter how late you are.
That being said: I advise you to pay on the 1st of the month anyway: that's when the landord expects it... why start trouble?