Definitely have her happily drinking her milk when you introduce solids, as it can make them constipated at the best of times - so I would either switch to formula well in advance, or get her onto solids and drinking water and then go to formula.
If you are doing BLW then it is easiest just to give the baby some of your food if they are awake when you are eating. They take such small amounts of food at first that you won't be replacing milk with food for ages.
I've found the advice varies hugely on this, but I have been giving solids one hour after milk and that has worked well. Some say give solids when they are hungry but I think that is outdated now, the baby will not realise at first that food fills her up and so may refuse because they want milk.
I would really think carefully before going cold turkey on the BFing as this is likely to cause problems for your boobs - a gradual cut down is better for you.
I would seriously recommend calling one of the bfing helplines and talk to a BFC on switching to formula. She should be able to talk to you about bottle refusal and how to reduce your risk of mastitis too.
you could give milk at the usual times she has milk and give food at your usual mealtimes. I gave milk at the usual times and then food about 1 hour or so later. Cant help with switching to formula as mine had formula from a couple of weeks old.
DD is 4 months and I'm starting to read up on weaning. I am hoping to do BLWand start when she is 6mo.
What I can't seem to find is advice on when during the day you are meant to give them food? After milk? Before milk?
Also, at the minute I am breast feeding on demand and want to stop BF and introduce FF at 6 months. Should I swap to FF before weaning, or just do it all at six months? She doesn't really drink from a bottle at the minute (despite having a bottle of expressed milk daily for the first 12 weeks) so I don't think I can slowly phase in the formula.