Cuttings can be taken at any time of the year. They readily root. I started one when I trimmed mine and now I have another Flowering Maple in a container. It has already flowered.
Keep in mind when planting that Victor Reiter is thought of as half hardy, so remember to protect this plant from frosts and low temperatures.By our calculations, you should look at sowing Victor Reiter about 63 days before your last frost date.
Flowering Maple