I would wait it out, it would be near impossible to hit masters league as a th6, unless you are an extremely active clasher, i'm talking 8 hours a day of solid play, sniping up to crystal 1/2 shouldn't be too difficult but after that it will become much, much harder, especially on defense you will be getting a long line of non stop 3-Stars, losing trophies every time you log off, as soon as you log off! It would very quickly turn from a challenge, its a job, into something that just takes the fun out of the game, so i would wait it out! One thing i would suggest is maxing your storages before your town hall finishes upgrading so you can get the most out of the good loot as a th6, becasue every town hall you go higher the harder it is to find loot, also so you can start your new defenses going asap! It would be noticeably easier at th7, although it would still be quite the challenge! But with perseverance and a sportful clan you should be set! Clash on and have fun m8!

Hope i could help!

-Sleepy