What's the appeal of larger crystals, are you just saying you want bigger crystals because that generally means pure, or because you want to fool the local junkie into spending more money?
Regardless if you would have UTFSE you would find, the faster you cool them the smaller they are, or in other words, If you cool the solution slowly you will get larger crystals.
i always dissolve my m in denatured alcohol then bring to boil...and then put it in icebox till i have crystals...then filter and wash with tone
Acetone should be unnecesar, recrystallisation should be the last step tin the yellow brick road. Obviously you are just chucking them in the freezer, if you add another hour onto your schedule you will get what you want, let it cool on it's own, prefferably on the heat source and then on the counter, then in the fridge, then in the freezer.