but isn't it countered by 222? AEC's timing is slower than 222 as far as I think.
sniper-gren-gren-T2-222 build will be counter the vickers UC.
I mean, should I play super defensively until the AEC will come?
Pretty much I think that's the idea. You want to minimize the MP bleed inflicted by the Sniper until you can get the proper counters out yourself. You don't want to bother with Vickers UC (at least until Patch comes since the default gun is better DPS wise) - just use the UC to occupy his Grens and soak damage. Conversely you use your Tommys and Vickers to cap around the Sniper and hold your fuel to get the eventual AEC. Somewhere along there you get your own Sniper and the counter-snipe war begins. That's probably the most efficient way to go about it unless you can catch the Sniper in a bad position (which you almost never will against any player worth his salt).
One thing to keep in mind is that even damaging the Sniper in an early engagement can be a big win for you as it forces the OStheer player to either
1. Waste resources/time on a super early Med bunker
2. Be much more conservative with his hurt sniper - limiting its usefulness in the early game