I’m trying to screw my toilet flange to my concrete slab. I have a masonry bit the same size as my screws 1/4 of an inch both bit and screws. Will that lead to my screws not having anything to catch and hold on? Should I use a thinner masonry bit?

I ask because I did one hole and I could easily lift the screw out of the hole with my fingers. I’ve been watching videos on mounting a toilet but no one ever covers this in a video.