Why wait 95% on a soft-fork? What happens if segwit miners starts mining segwit blocks right now?
Because of the way the soft fork works, unless a consensus is reached, the other nodes will simply reject all those blocks as invalid until the 95% is reached, so if a miner mines segwit blocks they end up being seen as invalid by all the other nodes and all the mining work is wasted. Once another 2 blocks are mined elsewhere on the network, even the miner's node will switch to the non-segwit mined blocks.
What I don't understand is that if soft-forks are backward compatible why would other miners reject it? Doesn't backward compatibility mean that new blocks are seen as valid by old clients? And if you wait everyone to update what is the benefit for soft-fork? Is there a con of Hard-Fork if it has 95% support?