How does your child with #Autism handle anticipation?

I pick & choose what I tell my daughter because I like to prepare her for some things but it's a nightmare when it comes to most things. Even if it's something positive or something she's looking forward too, she will have extreme anxiety about whatever it is & ask multiple times a day until the event happens. This not only drives me nuts, but it doesn't help her either. So, if we're going on a trip, I don't tell her until the day before. If we MIGHT get ice cream for dessert, I say nothing & just allow it to be a surprise. The only thing I really tell her about is her appointments in Oklahoma City. She has a calendar for those & already knows not to ask me, just go mark off the next finished day. She will stand there and count the days multiple times & even TELL me how many days left until she see's Dr. Jace again. Her anxiety increases within 1-2 days of the visit, (it's almost like she's EXCITED but she expresses it with whining, crying, screaming outbursts so we're still working to try & find a way around that.)  I try to be positive but sometimes it's exhausting.  

Anticipation is really difficult for my daughter, mainly because it is still really hard for her to deal with waiting for it to happen. If she knows exact day something is expected, then it is easier. But if the day is unknown, that is when an anxiety levels go up like that wave!