Lower Back Pain Due To Injury-can I Resume Activitys On Monday?

I’m 16, female, fairly active, used to be very active. I weigh about 118lbs and I am 5ft 2in tall.
I was doing a jumping spinning ‘around and down’ type kick, I don’t know how to but I tried. I didn’t land. I hadn’t realized I was falling, so I didn’t do any of the landing techniques, I just landed on my butt fairly vertical to the ground
I really want to continue with karate, because I may be able to take the test to be promoted fairly soon. How soon can I resume it?