well there is not really a set amount of time it takes to get a stalling call. quite frankly and as I intrepret the rule, any wrestler who purposly tries to stop the flow of action in a match is stalling. So for instance if a wrestler backs away from his opponent in neutral position then he could be stalling. This doesn't happen very often in the early part of the match becuase the referee considers this to be "feeling out your opponnent" however as an official if I see a wrestler moving away from the opponet then im going to call stalling. So the answer to your question is technically you could be called for stalling 10 seconds into a match if you blatenly try to stop the flow.