Mugo Pine help

I bought a mugo pine that was in a 6 inch nursery pit from a garden center a couple years ago. I planted it in the ground to fatten up some and it's at the size I want.
I'm in Z7 Alexandria, Va. So, my questions are:
!. What part of the year can I dig it up?
2. Do I leave the soil and treat it like it was collected in the wild or can I go straight to bonsai mix?
Thanks for any help

My experience with Mugo's is limited and not particularly good, but for pine in general you should probably dig in the spring and replace part of the soil with bonsai mix. the strength of most pines is in the roots so you shouldn't do too much at once. In addition, most pines have a strong symbiotic relationship with the Mycorrhizal fungi so you don't want to wash the roots. That being said, folks have successfully done the opposite of just about everything I said above. Hopefully, Vance Wood will chime in with some Mugo specific advice since done some great work with them.

I saw a article he wrote for a bonsai club on mugo's that was really helpful. Just waiting for the weather to break so I can get her out of the ground.

Normally I don't do much work on Mugos much before July.  You can work on them in the spring but you have to be careful not to traumatize the root system too much.  In your case you could probably just dig it out of the ground and throw it into a pond basket or colander for a couple of years.  Some photos of the tree would be helpful, when possible. It is a mistake in my opinion to think you are going to fatten the trunk on a Mugo by putting it in the ground if it has the common multitrunk configuration. Mugos tend to not do so well with common techniques used on a host of bonsai subjects.

Thanks Vance. Will try to post pics in a day or two. Basically I put it in the ground because I didn't know what to do with it when I got it. I usually do tropical bonsai's and Japanese Maples. Conifers are new to me bonsai wise.