You've still got a lot of white pistals, and as stated above, calyxes haven't swelled yet.
Can they go longer?? Yes they can
How much longer?? Depends on the plant and what it wants to do.
Personally, I wouldn't even start looking for a harvest window until those pistals turn and start to recede, there are a lot of white pistals yet, then you'll see the calyxes swell. It's all up to you, it's your grow, but IMO, at least 3 weeks before I'd start to consider bringing out the scissors.