Adding, because some people may not know:
Most of the time when you enter a maiden, claiming, or allowance race, there is no entry fee. Sometimes there is a very nominal fee going to different organizations, like aftercare.
But for stakes races, you pay an entry fee that’s usually a few thousand dollars.
Normally how it works is there is a small, non-refundable nomination fee of a few hundred dollars that gets you on the list of potential entries. Nominations usually close a few weeks before the race is to be run.
It’s common for connections to nominate horses to races they know they probably won’t run in, because if you miss the nomination deadline, you either can’t run in the race or it gets VERY expensive to enter. And… horses. They often laugh at our best laid plans. So it’s cheaper to nominate to any race you might consider in the future so you have multiple options.
Generally 5-7 days before the race, depending on the track, is when you submit your actual entry and your entry fee.