This is a really good question. I have met some people who wanted to move up on their certifications as fast as possible, many times just after getting their open water. I personally believe one needs time and dives before they should think about advancing. You obviously have that since you are a Divemaster. As an instructor you need to be confident and comfortable teaching people how to dive and advance themselves in various certifications That includes answering questions from people of all different experiences and skill levels and knowing that there are going to be divers who have more time and dives than you, yet you are instructing them. Basically I don't think there is a specific time frame.