Linda,
Yep, just plant it all!
They're especially good for those seeds that
should be direct sown, but aren't because of poor weather or soil conditions. Plus, they're very economical...I paid a dollar for 100 of the small lunch bags. I found that using the whole bag was a bit of over-kill, I was using way more seedling mix than necessary, so a couple of cuts and a bit of tape made up 2 planting pockets per bag. A little over half a cent per pocket.
The seedlings seem to love them. I'll try to get some more recent pix tomorrow....they're quite a bit bigger now.