From Recommended Pool Chemicals in Pool School:
Solid/granular cyanuric acid (CYA) should be placed in a sock and the sock put in the skimmer basket or suspended in front of a pool return. After adding CYA you should leave the pump running for 24 hours and not backwash/clean the filter for a week. Squeezing the sock periodically will help it to dissolve faster. Test and dose chemicals in your pool assuming the amount of CYA added is in the pool according to Poolmath. CYA can be tested the day after it is fully dissolved from the sock.
For liquid, as few use it, I have read some pour it in the pool and then brush well, and some pour directly into the skimmer. TFP, in general, discourages pouring anything directly into the skimmer.