Must admit, find it hard to understand why you disagree that the phone number can't mean a task can happen at any time.
1) Aiden calls asking for a photo of Sophia in sexy underwear
2) Aiden calls asking for a boob photo but don't show her face
3) Aiden calls asking for a full-frontal nude pic but don't show her face
4) Aiden calls asking for Sophia to meet him at the same spot away from school that they first made the arrangement, Aiden says to wear a skirt but no pants, she has to flash Aiden and friends
5) Aiden calls to tell Sophia to wear something really sexy and revealing at the party she is having for Dylan's birthday
6) Aiden calls to arrange a time to visit Sophia when no-one else home and Sophia has to strip naked and give Aiden a blow-job
7) Aiden calls to arrange a time to visit Sophia and this time fucks her
8) Aiden calls asking Sophia to meet him at his away from school hangout, she has to give him and friends a blowjob for last task (or more than a blowjob)
That would complete the tasks, all by Aiden using her phone number to arrange them, which can happen at any point of any day and it's not complicated, there nothing complicated about Aiden having her phone number, clearly, he asked for it so he can call her and give her tasks.
The first 3 tasks could be requested on the same day and any task could be located anywhere, maybe its in classroom, maybe its Aiden's hangout spot away from school or it's in Sophia's home or it just a photo she has to send.