Hi Emer,
Welcome to Microsoft Community.
I'm Hahn and I'm here to help you with your concern.
It's understandable to be concerned about the overlap between your device delivery date and the start of your maintenance contract. Typically, maintenance contracts should start from the date you receive the device to ensure full coverage. However, it sounds like the contract might have started from the date of purchase rather than the delivery date in this case.
You should contact the Microsoft's support to clarify this. Explain your concern and ask if the maintenance contract can be adjusted to start from the delivery date of your Surface. They should be able to correct any discrepancies or provide a resolution. Contact Us - Microsoft Support
I hope this helps. If there is anything not clear, please do not hesitate to let me know.
Your Sincerely
Hahn. W - MSFT | Microsoft Community Support Specialist