Thats gonna be hard for someone to answer for you specifically, but it makes sense to me to use em along with your belt. I've found with any kind of supportive gear, the more you use it the more you learn to get pounds out of it, to the point where first time I used elbow sleeves I benched less than without em. Now they give me 20ish pounds. Then again Im an idiot and it honestly took me a few years to figure out how to get pounds out of a standard weight belt. I still cant add anything to my DL with a belt haha.
Is this your first time with knee wraps at all? If it is then another factor is whether you will get anything at all out of em in time for your meet. You may not be able to adjust to the odd feeling and slightly different groove.