How long can you wait with a smack pack

I was wondering how long after smacking one of these you can wait to use it. I smacked a 1272 yesterday night and it is pretty well swelled today. I plan to make a starter today or tomorrow and brew on sunday.
I’m asking because I feel a cold coming on and may not brew as planned.

Years. After a while you’ll have to increase the size of the starter and/or do a multi-stage starter, but that doesn’t have anything to do with smacking the pack. It’s just a viability check.

I have had to cancel anticipated brew days - just put it in the fridge if it is going to be more than a few days. It will be fine.

I would put off the brewday on the basis that the yeast may not have time to chew through the sugars in the starter and multiply.