As a general rule, I don't haggle, and definitely no discussion on a first or a 2nd visit.
However once you've seen a girl a few times and you've got on with her, I have in the past discussed with them if they have special offers, etc, usually for a 2hr booking.
I've seen some girls for as low as £150 for 2 hrs.
Even with some of the regulars, if you frequently exchange text messages with them and find out they are going on holiday soon, I have offered to go and see them before/after holiday, depending
on their need for extra cash. Some require spending money for the holidays, others have already paid for their holidays, so may need extra cash upon their return to pay for any bills etc whilst they were gone, as it may be a while before threy earn more cash.
Similarly, I've seen girls who needed to extra cash for their upcoming birthday bash.
If you don't ask (politely and discreetly to your regulars), then you don't get.