Apologies if this is a common question but how long for glugged wafters?

I've had som sticky krill's in about a year now, some in the sticky krill pot and some coated in a zip lock.

Reason I ask is that when I first started using them I had a few captures and as I didn't fish through the winter and have started again not getting any interest.

Is there an optimum soak time?

TIA