Hi! difficult to say for sure, but two weeks or shorter. As you saw them playing football (or do you mean soccer?!* ), it is probable they could be felt a couple of day earlier, but without you noticing?
Cats usually do manage themselves quite well. But the wise is of course always prepared. Sometimes they DO need help, and it is hurry these times...
You are surely reading the other parallell treads?
Welcome, and
Good luck! *vibes*
ps. I see Buffy is from merry old England, so for our american friends benefit, lets explain it is what americans calls for soccer, we europeans do call it for - yes, football!