Hi there,
I'm a professional Drupal developer and loved to complete the project you've provided.
From the given description it seems, you need:
1) A new Drupal instance to be installed.
2) There will a little change in the design otherwise it'll be the same as the current one.
3) And the modules and all to be used from the existing one.
These all can be done, but please clear a few doubts of me:
1) Are you using Drupal 7 or 8
2) By the module, you mean only the contributed one or the custom as well.
The time mentioned is just for a safer side, otherwise, most probably it can be done before the mentioned time.
Please feel free to ping me any time for any clarification.
Regards,
Hashmat