Leider spreche ich kein Deutsch, daher kann ich nicht telefonieren
Maybe you want to call the English hotline then.
https://www.o2online.de/kontakt/
@eLtuke
i guess they can unlock the internet a few days earlier, but i think the day is already too close, to change the appointment onto this week or the next week. Wait for a moderator und see what they´ll tell you
Hello @eLtuke,
welcome to our o2 Community 
There are a few requirements that must be met for express activation:
if the activation date has been agreed with your old provider (Anbieterwechsel), it is not possible
The technician must either have already been there, or no technician appointment is required (as stated in the order confirmation).
A router must already be connected and the o2 homepage must be displayed.
If all of these things apply to you, you can request the activation to be brought forward to the next possible day (usually a maximum of three working days).
As you are not registered here in the community with a contract, we cannot reschedule the appointment for you. The best thing to do is to contact our customer service directly by phone.
Please let us know if you have any further questions.
Best regards
Giulia