#1 get it out of the B&B muck and into a good inorganic substrate
#2 let it grow and set flower buds
#3 enjoy the flowers next year and then chop it (chop it good!)
Maybe you don't wanna, now that I've said that.
I have had mugo, I still have mugo. IMHO, one should not pay much for a decent mugo (i.e., less than $50). Buy the stellata - they are a kick. Meanwhile, look for a reasonably priced pine. Mugo is okay, but p. thunbergii and/or p. densi are far better. Buy some 0-3 saplings if you can (about $15 a pop) and have a ball raising them - they grow fast and allow one to really create 'their tree'. Now that is F U N, IMHO. P. nigra (Austrian/european black pine) are just as fun to grow, but offer bigger challenges controlling needle size as refined bonsai. P. sylvestris (scots pine) is maybe better and is handled a lot like mugo, if that matters. You might be able to find a bigger one with some nice bark in a garden center.