Hey Nemeseri, Great to hear of your interest to climb Whitney, but in response to your question, there is no honest way to answer you question on probability of success without knowing more about yourself and partner.
Have you done much climbing/hiking above 10,000ft before or higher? What does "long hiking experience" mean?
If you've never been to that altitude before or on any long (15mi+) climbs above 13,000ft with decent vertical gains (5,000ft+) carrying a pack, I'd suggest waiting on Whitney until you can get up to the Lone Pine area with 2-3 full days before your anticipated climbing start and budget a rest day up high the day before your targeted Whitney climb. You could be fine and have zero problems hiking up and down in one day, but you could also have a really bad day if you came down with AMS or worse.
Better to prepare better and have an extra day than to rely on pharmaceuticals to get you up and down, though Diamox should, on paper "help" your body get you up the mountain theoretically.
Altitude does funny things to "fit" people sometimes and it's hard to predict how you'll feel when exerting yourself up high.
While "just a walk up" on the Main Trail, Whitney can punish the unprepared and doesn't care if a climber is short on time.
Have you climbed San Gorgonio or San Jacinto? If not, since you only seem to have two days (?), I'd recommend looking into those to peaks first - they're both wonderful climbs and will get you to 11,000+ft. White Mountain Peak (14.265k) would be a great test of altitude for you, and while shorter (15mi), will let you see how your body reacts up high.
Cheers and Good luck!
