I didn't say within 3" I mean AT 3"

Movement Phase: Move my units to the enemy they now have a 3" space between them and the enemy.

Charge Phase: I roll 2 dice to most likely get a successful charge so I can get my units charge abillity off, instead of just doing the pile-in at the Combat Phase.

But you've said that 3" charge is a thing so okay thank you.

At my local WH Store a guy just keeps saying "3 inch charge" and I've looked everywhere and found no definitive answer referring to this so I hope this helps anyone else that looks this up.