Yeah, that'll happen. A mild text conversation can be fine. Just a couple messages in between... if, say, the date is five days out, on the third day after you've set the date, a little rapport text and a few back-and-forth messages can do the trick. For a rapport text, just write a Standard Scheduler Text, but leave the scheduling question off. So it's:
Then trade a couple texts when she replies. Don't get in too deep.
My personal preference though is if she won't be free for 4+ days, to delay setting details for the meet until we draw closer.
Once you confirm the date, and it's far off, you tell her you'll ping her when you're closer to plan the details.
That's like this:
There's a non-zero chance your "Let's set the details" text several days later results in a flake if she's cooled off. But in my experience it's no greater than the flake rate for girls you set the details for in advance, then call or text in the interim to keep things warm.
There are two advantages of delaying the details until you're close to the date I like:
No risk of the interim conversation going weird or derailing things
You avoid the "she liked the date idea four days ago, but now she doesn't like it" problem, because you don't set the idea until a few days before the date
Up to the guy, of course. You can do either: set the details, then have an interim chat to keep things warm. Or pick a date but delay setting any further details until the date draws near.