When am I ready for Masters ?from newbie

Hi everyone, my first post here! I have no experience in any formal swim training/competition whatsoever. Like alot of people, i was interested to attempt a first tri-athlon and therefore I dragged myself to the pool. My experience in swimming was from elementary school, swimming everyday in HK (beach)- is that the same as open water, not sure what the difference is. Everyone said that open water swimming is different from the pool, does swimming at the beach count? Anyways, I am fairly good with breaststroke endurance wise, I haven't really count or time myself, but my guess is I can do 30x 50meters okay. However, I can't do other strokes. Don't know what's wrong with me coz i cannot get pass 25 yards with the crawl (breathing becomes difficult). Not sure if this is aerobic related or just my technique coz i can do it with breaststroke. I really want to polish my front crawl and from all i read, everyone recommends the masters swims. Can i join the masters if i can barely do 25 yards of front crawl? I don't want to having to stop and cause traffic jam in the slow lane all the time. Should I just practice in the pool until i can do 100meters before joining the masters so that I won't upset anyone?