You could do Thursday as well. You set late on Sat.- Wednesday evening to Thursday evening would be day 18 for you. Some people lockdown early on day 18 some people wait until the end of day 18 and there are still others that lockdown early day 19. I've even heard of some people that hatch bantams will lockdown late day 17. It doesn't have to be a precise time.You're hatching chickens right? You said you set on Sat the 14th. Actually Wednesday would be the 18th day.. not Tuesday. with Saturday being day 21. Sorry about that.