a 24 human warrior...
For that one we're gonna have to look at an experience chart... which there happens to be one of on allakhazam.com, riht here:
http://wow.allakhazam.com/db/guides.html?guide=362
(I hate looking at this chart because it makes me feel shitty for how long i still have from 50->60)
Now, this really only works as a rough estimate based on the fact that most people fight mobs equal to their own level. Also to take into account downtime between fights, I'm just going to multiply the whole equation by 3.
Basically we want:
Total # of fights at level 60 - number of fights at level 24, this givers a rough estimate of how much shit your going to kill:
(Just so you know, at level 24 you've done only the first 15% of the way to 60 if you count total kills needed, experience is similar, but the numbers are huge and this computer doesn't let me use its calculator)
Total comes out to 13940 kills remaining, now don't get too scared about that number its a rough estimate. Now for a warrior I'd guess your going to get fights running to at most 30-45 seconds on average, lets say 38. So we multiply those... 529720 seconds, x3 because we're pretending you have twiec as much downtime as uptime (which is almost not enough).
That we divide by 3600 for hours and 24 for days, we get: 18 days.
Don't forget though that A: that's a completely offhand rough estimate, B: i'm not counting instances, C: warriors can fight multiple mobs at once like druids and take them all out in the time it takes others to take just 1 or 2 mobs (groups of 3->5 usually), D: blah blah blah.
Either way, according to that chart levels 0->60 would take 21 days, if you cut that in half and add a bit, I'd actually think you have more like 10 days left.
Don't worry about time and just grind.