Hi Yubit,

It is my understanding... the new ICO plan outlined in Whitepaper 11, has adjusted it so it can be a total of 4 BTC (no matter when contributed) for the 20% bonus. 

PS. After ICO, voting membership levels require a 2 BTC minimum, during ICO, only 1 BTC is required to be a voting member.  I learned today that with Dash voting members must own a reserve of 1,000 dash to vote.  I love the Adel model giving many the ability to have a voice.

Jess