This is the major challenge soloing these...the named spawns. Jibbers always spawns shortly after you get your first 100 crystals, so sometimes it's a good idea to head back to center, and while waiting for him to show up, maybe start on a line headed the opposite direction if you have extra torches, but don't connect this line till they're done with what you're currently mining.
I ran the cove solo once this year (also low level...I think 5 when I did it) and Gregoire slaughtered most of my crew in the closing 3 minutes as I was setting lines down in the bowling alley.