Hi Maryam,

it seems, that you not familiar with the 8051 microcontrollers.
To connect several I/O on the 8051 was possible and named memory mapped I/O. You be able to connect up to 65536 peripheral devices in this way. So you must never fear, that the port pins are not sufficient.

But my preferred ADC was the MAX127 with 8 channel input, 12 bit resolution and four selectable input ranges.

And as display I use the MAX7219.

Both are serial, so you need no memory mapped I/O.
You can find many stuff about these two devices on the web.

To solve your timer question, please look on the tutorial.

In my opinion only one month time to finish looks damned short, since it seems, you have already nothing done on the software.
Please watch, hardware need about 10...20% of time and the remaining 80..90% consumed by software developing.

Peter