How do you make sure you have enough yarn at the end of your sock, to close the toe?
Here's what I do; I'd be interested to hear other solutions too.
Once I'm on the last return trip (cylinder moving counter-clockwise) of the toe, I stop with the yarn carrier in front, lower all the back needles making sure their latches are open, and cut the sock yarn at the base of my table -- it comes out of the sock machine, up through the yarn tensioner, and back down to the ball on the floor; I cut it at the table height, the remaining foot or so attached to the ball on the floor falls back to the floor; so I must have about 2-3 feet of yarn not knitted hanging there from the yarn tensioner still attached to the sock on the machine. To that now cut end I attach my waste yarn with a square knot.
Then I continue knitting until the sock yarn is under the last needle before the hash mark, but that needle hasn't done much (if any) of its downward trip yet. I take my "dental tool"/pick and pull the rest of the sock yarn in, up to and including the knot tieing it to the waste yarn, and use a wooden clothes peg to "weight" this yarn inside the cylinder. OK. So, the next stitch after the hash mark will now be knit with the waste yarn. Then I knit 10 rounds with the waste yarn and start the next sock (ok, so usually I take the sock off, close the toe, evaluate it, _then_ knit the next sock...)
Let's see ... yes, usually I knit the toe without the ribber in place; not sure how I'd pull the yarn through easily with it in place, but it could be done.
The square knot is so that it is easy to separate the sock and waste yarn later -- if you pull on both ends of one string in the knot, the knot turns into a reverse-half-hitch-half-hitch knot combination, which easily slides off the pulled yarn.
(posted by me to sockmachinefriends, this day)