Batrider can achieve level 6 in 3 minutes 40 seconds via dire jungle...

Did the math today... yes this is very possible and most importantly. You can gank the enemy carry who is level 2 almost immediately afterwards and get a free kill and snowball out of control. This can only be achieved on dire side due to the unique geometry and the following creep camps do not grant enough xp complete this if multiple spawn in the time limit: Wildkins (large), centaurs (medium and large) and ogres (medium)

STEPS:

1 buy a courier (private use) and a single tango 2 level up firefly at level 1 3 destroy all the trees directly south of the tier 2, the ones just to the east of the big cluster can stay 4 Destroy all the trees on the north, east and south sides of the small camp 5 wait till the creeps spawn and immediately cast firefly over the small camp and clear it. 6 Stack the large camp at 0:53 (if a support stacks the medium camp at this time, creep camp type can be ignored) and eat a tree while flying away 7 Draw the agro of the small creeps and draw in the lane creeps to clear the small camp (this is one of the harder pulls in the game) 8 as the small camp is about to be cleared, agro the medium camp so that a creep will run over the stairs as the final small camp creep is killed. 9 Kill this camp as quickly as you can via firefly 10 repeat steps 6-9 until the 3 minute mark when the large camp has stacked 4 times (please note, the support can go back to lane after stacking the medium camp once 11 Stack napalm on the large camp a few times and then firefly over it while clearing the small camp at the same time this way.

It takes a bit of practice, and you must buy a bottle as quick as possible to sustain the firefly, the private courier can be used to bottle crow this in the mean time.

GL pub stomping