new members joining here must think what a load of old cynics we all are. Whilst a number, maybe the majority, of WG's are like the way they have been portrayed in these thread (and they have made us both streetwise and cynical) it is important to remember that not ALL WG's are like that.
I have, in the past, paid a regular a bit in advance on a few occasions - (just the one WG but 3 or 4 time). She was a mum of 3 struggling to get by, and a part time WG when the kids were at school. She lived in an area where people noticed coming and goings so i fully believed her when she said she saw just one guy a day and for no more than 3 days per week so was not "linning them up" as some guys would have you believe. On a couple of occasions she asked if I could pay part of my next session in advance - for the electric meter or similar. I did on about 4 occasions and never had any problems at all and no fall off in service level - in fact, if anything the other way. Even better!
This was in the days of being about to pay £50 in cash into her bank account and it worked well for me. But I would not have done that for others. well maybe just one other regular - but it was never asked.
so like most other things, ask yourself the question - do you trust her completely? And like gambling, never risk more than you can afford to loose if it goes belly up!