Piece of cake put the tag end of the string in the grommet hole before tensioning the anchor string. If you string then comes up to short to tension use a starting clamp as a bridge to pull tension. Works every time.
Also if you are using gut for your crosses it is sometimes difficult to get the flimsy sting in the skipped grommet holes when the holes are covered by the tensioned strings. If you pre weave the top crosses before blocking those holes you will never have a problem.
I have the ability to drive people crazy, not sure if I was born with it or I learned it but I'm damn good at it.