I would wait a bit then a quick text saying hope you're doing ok or dog is coping or our journey home was fine or something like that. We didn't call or FaceTime, waited for her to call us.
It is important of course for them to know they are loved and missed but I definitely feel it's an area where when it comes to the drop off and early days we, as the parents, can try and step up and keep our feelings away from the kids. Totally right to be up front with them beforehand about feelings and anxieties and allows them to do the same but when it comes to the actual separation We want them to enjoy their space and work through their own feelings of missing us without worrying about how we are doing. When we left dd1 at Dundee we just about kept it together for the hugs and then I cried all the way back to the car and in the car but she couldn't see any of that. Db was driving, he alleged he was fine....