During their wilderness journeys, when did the Israelites set out?

Answer: When the cloud lifted

Whenever the cloud lifted from above the tabernacle, the Israelites set out; if it was not lifted, they stayed.

“Whenever the cloud was lifted from above the tabernacle, the Israelites would set out through all the stages of their journey. If the cloud was not lifted, they would not set out until the day it was taken up.”— Exodus 40:36-37 (BSB)