the maximum tire inflation for your tire is on the side of every tire including yours. Depending on the type of bike you have and the kind of ridding you will be doing will depend on how much you need to inflate too. You may not want full or max pressure for road ridding or you might and this will depend on your ridding style and the terrain you are on. What kind of bike is it? What tires and where will you be ridding it? Tell us that and we can tell you more. Check them at least every ride before you leave and when you come back or every other ride at least.
Edit : my experience tells me that you probably dont want to inflate to max pressure of 120psi.....if that is what your tires recommend since the pavement is rough or semi. You might want to try 90 to 100 psi and see how that does and check the tires and pressure after every ride. Also get some spare tubes and tires, sounds like you will need them!
Edit 2: sounds like your tires are rated for a max of 80 to no more than 90 psi so run short pressure around 15-20 psi less than the max and see how that does and that will help to smooth the ride a bit. Next month try max pressure or 5-10psi less and see which one you prefer over the other and how well the tires hold up.