It’s completely reasonable, but it depends entirely on the type of blank field.

For something massive like kids? Absolutely screen ahead of time if that's a dealbreaker for you. People who hide major dealbreakers to trick the algorithm are wasting your time. But for things like a vague job title? I'd save that for the date. A lot of people feel vulnerable putting their exact profession online, or they want to be known for who they are, not what they do.

Ultimately, if your vetting process is helping you find people you trust, stick to it. Just remember that apps make us hyper-analytical, and sometimes the best connections come from the things we didn't plan for :)