Students in the wedding

I have children and my friends' have children however they are all too old to fulfill the flower girl/ring bearer roles. We are skipping those role's all together. My daughter (11 by then) will be JBM and my son is walking my mom down the aisle (he doesn't want to stand up front as he is on the autism spectrum and is uncomfortable being center of attention). Best man will hold the rings and flower girl role really isn't necessary ever aside from being cute. Totally up to you but no one will notice these roles being gone.

In the very least, I'd wait until early fall of 2020 before doing anything about this. Having kids in a wedding has it's challenges and especially since the children you're considering aren't relatives or super close to you, I'd wait and see how you feel about it when the wedding is much closer. As a teacher, you realize how much kids change developmentally in short periods of time. The now adorable 8 year old could be a surly tween in 18 months, and that cute baby could be the poster-child for "terrible twos," or, you might be even closer to them and their parents by then and won't be able to imagine your wedding without them! I'd wait and see. Daughter had four children (all siblings who are relatives) in her wedding: 10, 8, 6, 4. She kind of felt like she had to ask them. Honestly, throughout the 18 months of planning the kids and their mom were the ONLY thing she stressed about. The day of worked out fine, but the youngest (4 yrs) literally SHRIEKED throughout the rehearsal and rehearsal dinner, and seconds before they walked down the aisle for the ceremony, the 10 year full-on SLUGGED his 6-year old brother REALLY HARD in the chest.... Only the bride and FOB witnessed it because they and the kids were the last ones getting ready to walk down the aisle. When daughter told me about it after the fact, she said she stood there in shock waiting to see if the little brother was going to burst out crying and/or fight back. Luckily, he was apparently used to that kind of thing and just walked down the aisle as if nothing happened, but daughter had a momentary panic. Cute kids in photos aren't necessarily worth the hassle, especially if they aren't close enough to you to be worth any potential aggravation they may create. (Also, in terms of the practical aspects of the day, just before the wedding party was to be announced at the reception, the youngest LOUDLY declared she wanted to go to bed, and then slept on a lounge chair for the rest of the night, and the six-year old walked around the reception in a daze all night with one thumb in his mouth and his other hand tucked into his pants.... The older two had a blast dancing, but it was all kind of a crap shoot.)

I know you say you know them because they are (were?) students at your preschool, but if you keep them outside of school, I do not think it would be inappropriate. Of course like others have said, as long as their parents are invited. I invited a family that I used to babysit for because we were all so close. Their children are too old now to be in the wedding, and I have close family for a flower girl. But regardless, I think your situation is fine - just have a conversation with the parents!