Karazhan up to Netherspite

Hi guys

So I raided with a pug group and killed shade of Aran, but someone had to leave after and now I’m left with my save up to Netherspite.

I’m super struggling to find people to start from here - is this a common experience for people?

When’s the best time do you think to find people to start from here.

Also side question, does killing night bane lock you out of the other bosses ?

Thanks