Managing incubation must begin with planning the timing of bee hatch and their release. When bees are released they must have immediate access to food, in the form of nectar, or they will leave the field in search of it and not return. If bees are released too early, before there is sufficient bloom, many will be lost and both bee and seed yields will decline. On the other hand, the earliest blooms produce the largest and greatest quantity of seed pods and are most likely to mature into seed before fall frost. The later the bees are released into the fields, the more potential see yield will be lost. The ideal time to release bees is when the field is in 40% - 50% bloom. This is determined by picking random stems and calculating the percentage with at least one bloom. Correct timing is important!
Attached is a Calendar of Leafcutter Bee Incubation