This is only a suggestion; I have not tried it myself, but this is what I would do. Get a paper straw wrapper. Wrap the parachute around the tube of the bottle rocket. Tie it there with the paper straw wrapper. RIGHT before you shoot the rocket, wet the straw wrapper, so it is very, very fragile. The force of the rocket being launched should tear it, so when the rocket hits apex, the parachute will be deployed. Try it out now, so it won’t bomb on you tomorrow. You may need to cut the straw wrapper in two, lengthwise for it to be weak enough to fall apart when you want it to. Experiment. Best wishes.

i made when when i was in elementary but i forgot how i know you cut out a pop 1 litter pop container and you use baking soda and water