What does it mean when a girl says "let me check my schedule"?

Read the rest of the message she sent alongside the phrase. If she said something warm, asked you a question, or referred back to something you talked about, the schedule line is most likely just logistics. If the message was short and flat, or she only answered the part about meeting and ignored everything else, that tells you more than the phrase does.

Notice whether she named a day or a rough window, even loosely, like "maybe Thursday or the weekend." A direction is a good sign. A pure deferral with no days at all leaves room for a polite no. Either way, the phrase alone doesn't tell you much. Her engagement in the rest of the chat does.

The reply that tends to work is short, keeps the tone you already had, and offers a small, concrete option she can accept or change with one word. It should sound like you're fine with her checking, not waiting on her answer. Make it easy to reply to in a sentence.

A reply that just says "sounds good" leaves her with nothing to act on. A reply that lists four possible times forces her to pick and feels like a form to fill in. Aim for one or two options, framed loosely, with room for her to suggest something else. Save anything else you want to say for a different message.

If she said she'd check and get back, give her the rest of that day and the following morning. Most people reply within a day when they're interested. If it's been about 48 hours and there's nothing, send one light message that mentions the plan without asking why she hasn't answered. Make it easy for her to pick the thread back up.

If that gets no reply after another couple of days, stop. Silence after two attempts is a clear answer, and chasing it is the fastest way to make the interest disappear entirely. If she does reply later with a real day, you can pick it up as normal without bringing up the gap.