What I want to know is should I;
1. Candle prune now to give the backbuds plenty of time to form before winter,
2. Candle prune around july 4th as I’ve heard suggested to give the plant as a whole more time to store energy, or
3. Put them in the ground and stop messing with them for a while.
The thing I’m worried about is they are already leggy and I want them to start looking like something of value.
To strongly induce backbudding you want to remove hardened foliage to collapse the auxin flow from that foliage down the branch. So, if this is your primary aim, wait for the new needles on the foliage to harden, then cut them off, right down to the base. You can also cut further back as long as you are leaving plenty of needles - new buds strongly tend to form only at the base of existing needles and not on 'bare wood' where there are none. You can also cut a little bit less, keeping a few rows of fascicles if you prefer or a bit more as long as you are keeping plenty of needles. Vance Wood, the preeminent mugo authority, advises to remove the new growth for 3 successive seasons and then let the 'tree rest' in the forth. He instructs us to control growth in the forth season by candle 'pinching' or breaking off a portion of the candles (ala Japanese white pine pinching).
Mugos will not produce a second flush like black and red pines. They will only set buds for next season's candles, so 4 July isn't important. My guess is that it will be in July, but could be as late as early August for the new needles to be hardened. Then you cut off all that new growth.
Even if you put them in the ground, you MUST tend to the foliage or you risk winding up long branches with puffs of foliage only at the ends which, for all practical intents, is impossible to reverse.