2 things to say:

1- yes, i just sent a 5:30 run but i realized that it could be improved

2- you can tell i got the max stacks bc in 5:25 i had 99 armor, and in 5:26 i got the max stacks, activating the part of the passive that reads "After reaching maximum stacks, Garen gains 10% bonus armor and 10% bonus magic resistance."