Once you meet the Simple standard is a good time to branch out and work on other skills, but can certainly try them anytime. Depends a lot on whether you have an instructor available to work with you. Your risk of injury increases if you do things incorrectly, and even more if you do them frequently or progress too quickly with weight.
S&S is a great program to get started, and plenty of support available here!
S&S is a great program to get started, and plenty of support available here!