I just got done with Taris, only quests I didnt do were the heroics.
Went from 18 to 23
Nar Shadda will make up for that. It's supposed to be 20-24 but the amount of xp you get there really isnt all that much.
The hardest part will be saving the 40k credits to get speeder training at lvl 25
Ive only got 20k saved so far.