Can you explain how exactly do you want to implement this voting system?
It would work the same as Heavycoin, with votes being proportional to hash-rate applied, and values applied by an average of votes over a look-back window.
I mean will it take into account only last 2000 blocks or all the blocks (will all already mined blocks have default voting parameters then?)
It will take into account only blocks within the set look-back period. There would be an initial "seeding" round where parameters would be at default but with votes being collected into blocks before the first parameters get set. Old blocks would not be considered.
Also, I think maybe it's wiser to wait until mining distributes well and more exchanges add moto before implementing this voting system?
This is all being speculated under an assumption that mining distribution will naturally continue to balance itself out over time, to a point, from the existing anti-warp, particularly after the target interval is made shorter at the block 210000 fork. I think the bot started to hit its limits around the 0x1F010000 anti-warp target, implying that we are already close to what the anti-warp will do "on its own" as an "anti-bot" mechanism. (Of course we still need more miners to step up to the challenge and claim the hash-rate that is now available to them... or we need someone to publish a capable bot for broader use.)
How many exchanges we are on does not seem to be at all a factor in the decision.