Hello; I no longer place tanks on carpet after some ruined carpet and damaged floors. I level with a long carpenters level, two feet or longer if you have one.
I first level the stand without the tank with shims. Carpet can throw the process off a bit. I use solid shims usually made of metal in particular with large tanks. After the stand is level I place the tank on the stand and check the level again. If still true enough I add some water and check again. If the level is off at this point I empty the tank and start again. I keep checking the level as the tank is filled.
If you are determined to place the tank on carpet regardless of the likely damage, I would leave the tank set with a bit of water for some time to see if the carpet and pad compresses enough to change things before filling up.
Good luck, on carpet you will need it.