The question looks incomplete as written (“how / late / can / 1”). It is not clear what “1” refers to (for example: a period, a flight, a payment, an assignment, etc.).

Clarification needed

To give a precise answer, more context is needed. Please say what you meant, for example:

• “How late can a period be before I should worry?”
• “How late can I check in for a flight?”
• “How late can I pay my rent/credit card/utility bill?”
• “How late can a 1‑year‑old go to bed?”

Once the missing context is clear, a specific, accurate answer can be provided.