altitude sickness can occur at relatively low altitudes - the key factor is your rate of ascent and at what altitude you are initially acclimated to.
A slow and steady pace, with plenty of rest breaks and paying attention to breathing can alleviate the need for meds. Paying attention to your rate of ascent with an altimeter is helpful too.
If you are going to cover 3000+ ft gain in a 24 hr period above 8000ft, meds like diamox may be something to consider.
If you are going to altitudes about 13k, with little time to acclimate diamox might be a very good option. Even with altitude meds - take it slow and steady, breathe deeply and stop to rest on a regular basis.