Help - Project Planning

Hi experts!

I'm on a client and did the following needs: There is a project that should be done within four months, and within that period there are stages that must be met within a specified period.

eg:
- Send request within 15 days
- Issue technical opinion within 5 days
- Issuing quotes in 15 days
- Issuing purchase order in 10 days

Approaching the deadline of each item we think the possibility of activating the workflow to notify the responsible X there pending to be tratatadas.
Exists within the module PS or PP something that can be worked out for this purpose?
Unfortunately do not know anyone that module to ask a help, so if anyone can at least guide me, it'll be of great help!

Thank you and sorry for my english. It isn't very good!