Choose the timespan and on which days a minimum number of instances should be kept alive. If the To-time is before the From-time, the time range will wrap around to the next day. E.g. From 23:00 to 06:00 with Monday selected would mean that the instance(s) would be kept up from 23:00 on Monday evening until 06:00 Tuesday morning.

A cloud-level Hot spares by label rule obeys this too: outside the time range this AMI holds no hot spares, and any it is holding are released at their idle termination time. A label served by several AMIs keeps its spares on whichever of them is inside its own time range, so a label can be covered by one AMI per shift.