German has two negatives and they are not interchangeable. Kein negates a noun that would take ein or no article - Ich habe kein Auto. Nicht negates everything else, and goes at the end of the clause or directly before the word it targets.
Examples
- Es ist noch nicht ein Uhr.
- It isn't one o'clock yet.
- Ich arbeite sonntags nicht.
- I don't work on Sundays.
- Ich habe keine Zeit.
- I don't have any time.
The mistake to avoid
"Ich habe nicht Zeit" is wrong - a bare noun takes kein, not nicht.
Where this fits in
Numbers, days, time, German A1: Count, talk about days and months, give the time, and handle numbers in real situations.