You can graft as early as you like. Show your participants how to graft
the trees. Tell them to take them home and plant them in flower pots
with good potting soil. Place them in a heated room in the house. I
usually use a north window in the living room. Any place that stays at
room temperature. Avoid a south window to start. Once growth starts,
trim sub-graft growth and trim to one above-graft sprout. Once growth is
good, move to a south window. Plant outdoors after last frost. Works
better than commercial methods.