I put a new filter cartridge in and then replaced 30% water, is that okay?

its a 10 gallon tank with 4 guppies, 4 neon tetras and 2 [VERY HORNY] ivory snails. i put a new filter cartridge and then cleaned the plants, ornaments, and gravel. i stirred up the gravel and replaced 3 gallons. i remember a year ago when i first got the tank the pet store worker said to never do a water change when you add a new filter cartridge. will my fish be okay?