You will need to add CYA to your new pool when it gets filled. However, trichlor is not the best way to do it, even if it's cheap. Trichlor is really acidic, for starters, so depending n the fill water you might also end up needing a bunch of baking soda right away which would cancel any savings. Also, you wouldn't want to add it too fast lest you overchlorinate, so it could take a couple weeks to get CYA up where you want it. So I'd pass on this stuff.
Also take a pass on any liquid chlorine, because it deteriorates in storage and by next spring it may just be expensive salt water.
Do watch for stabilizer/CYA, pool toys, maybe brush and pole, leaf skimmers, etc.