time frame 
noun
A specified period of time in which something occurs or is planned to take place: the work had to be done in a time frame of fourteen working days...
- I think that two years is a reasonable time frame to make my dream a reality.
- Being as specific as possible with the time frame will help the plan be successful.
- Unless we move to build it within a reasonable time frame this money will have to be repaid to the developers.