I'm going to pay rent on the 19th. Its due on the first. Late fees apply after 9 days.
A typical written lease will have a date after which there is a late fee, and a date after which you are in default. If payment is made after the default date, and the landlord doesn't accept the subsequent rental payment, your payment is late and you can be evicted for nonpayment. There may be other defenses however. If the landlord accepts rent after the default date, it would negate the default unless the landlord accepted it as "use and occupancy" only, in which case the eviction could proceed. There may be a genuine issue of fact however, on whether the payment was rent or use and occupancy, and that would be controlling.See question