The whole point of DateFinder is to show you are free on a particular date so that you can be matched up with other people who are also free on that date. DateFinder is not intended to be used to see who is free so that you can work out if you're free too.
Listing yourself on DateFinder shows people that you're serious about doing something.
If you do not wish to let other people know that you're interested in going on a date on a particular day, then you'll need to start conversations to see who is free when you are.