You can try it full length, but if seems loose in the smallest cogs, shorten it. Not a big deal to do so and I can swing by to help with a chain tool.
I love quick links, but make sure it's a KMC that works with almost all chains. Much easier to take apart if you ever need to replace a derailleur or anything. The Shimano pins are not really reusable.
Also, buy a KMC chain next time!
The Shimano [attachment] pins aren't re-usable at all. If you try to push it out, you'll destroy the side plate/break your chain tool's pin. They aren't meant to be pushed out.
I don't particularly care about the pins vs. quicklinks thing...the only reason I remove a derailleur chain personally is to pitch it in the trash, but YMMV. Rear derailleurs can be installed without breaking a chain, and many mountain bikes no longer have a front derailleur, so...
FYI
@Kaleidopete , the CN-6701 is intended for road usage. There is no reason you can't use it on a mountain bike (and I have no idea what you're using it on, anyway!), but it is optimized for Shimano road chainrings. It's only meant to work with doubles, by the way...the triple-optimized chain has symmetrical outer plates. The two chains perform markedly differently, when you try to use them on the setup they are not meant for, but still perform well enough for it not to really matter. It's asymmetrical in its design, by the way--the shaped (and engraved) plates must face outward for it to work properly...it'll shift very roughly if you put it on backwards.