Certified GKH Gardening Expert
There would be no way for me to tell you what month, exactly, to plant these without knowing your locations. You can plant indoors as long as the growing media remains above 80 F and below 86 F, and outdoors as long as the soil is between that range also. Whichever month in your area stays like this, is when you will be able to plant.
Here is an article that will give you more information: https://www.gardeningknowhow.com/ornamental/flowers/desert-rose/desert-rose-propagation.htm