Ok y'all get a sort of precis of warping a rug loom tonight.
You set up a warping board, like a peg board. However big your blanket is going to be, divide it down into manageable hanks, like 20-50 warp strings per hank. You stretch each one in a z pattern on the warping board so they're all piled up but no strings cross. Then you pull all that off and loose weave it into a chain so you can pull the strands out but the whole hank doesn't tangle.