but how long did it take to get the first reward? And what happens if you withdraw some ECA?
Coin maturity (staking symbol turning green) is reached exactly 24 hours after first deposit. When you get first reward (aka - mine your first block) depends on how many coins you have, and how many other coins are staked by someone else (thus the function of "your weight" vs "network weight".
If you withdraw some ECA, it depends. You can only spend whole inputs (stacks) of coins - but if you send them in several lots, you should manually select the input that is closest to the amount you want to send - then only this position is reset, and the change starts from zero - all the other positions remain unaffected.
Is this from the ECA wallet or from CoinsMarkets?
Thanks!