Round 3 is the fastest most early aggression should hit, and in many circumstances it actually hits round 4 if the other player plays defensively. Faster aggression usually puts you behind in mana and actions, and is generally inefficient. A Grimson rush hits round 2, but Grimson is fragile, so you need to be extremely careful with him.
Let's say you open with
Round 1 (19): Sprint to NC -> Enchanter's Ring (17)
Round 2 (26): Lord of Fire -> FD Cheetah Speed (1)
In this case, you'll still need to use Force Push or Teleport in order to land an attack in round 3 if your opponent is still in their start corner, but you can attack if your opponent has moved out at all.
One of the fastest aggressive options I've thought of was a Forcemaster opening that attacks on round 3 with a Steelclaw Grizzly, but I've still not tried it. It would go something like this:
Round 1 (20): Sprint to NC -> Battle Forge (12)
Round 2 (22): Enchanter's Ring -> Steelclaw Grizzly -> FD Cheetah Speed (3)
Round 3 (13): Force Ring -> FD Bear Strength -> Force Pull -> reveal enchantments -> attack with Grizzly (4)
You could opt for armor instead of the Force Ring, but either way you're in a position to cast Galvitar and start doing quite a bit of damage. I like that more than other options that use position control to get an attack in round 3 because Force Pull is a much cheaper investment than Force Push/Teleport.
Starting to spam attack spells in round 2 or using Divine Intervention/Teleport to start attacking with a melee creature in round 2 puts you behind.
I don't think Force Pull works here: it only targets something 2 spaces away, and the grizzly could reach them anyway!
But if you want all out aggression, attack with the mage themselves! A forcemaster with initiative can:
Turn 1 (20): Cheetah speed on self (5), sprint to Near Centre, Battleforge (
7 left
Turn 2 (17): Battleforge casts Ring of enchantment (1), bear strength (4), run to adjacent to opposing mage, force pull (1)
Turn 3 you're placed to deploy galvitar on yourself and double-attack them. To reduce this to a single attack they have to teleport away with quickcast or similar, wasting mana and still getting hit. And you have mana to burn, meaning you can mind control big creatures, keep using the battleforge for attack/armour... whatever you want!
Not saying this is ideal: but having faced slow builds and fast builds, the latter can definitely be intimidating!