My bitch has come into season earlier then expected!!
I normally have a bacteria vagina done as soon as she comes into season to check for any germs before mating takes place and Antibiotics are prescribed if needed.
I have just phoned my local vets who can see her tomorrow at a price of £103!
I then phoned another vets further away from me but I have used before and they can see her today at the price of £79!!

Shocking price difference!

I recently had a bitch swabbed prior to mating her.  Can't say exactly how much it cost as I also had an older bitch vaccinated and purchased the CHV innocualtions, but I did think my bill was higher than I thought it would be - perhaps lab charges have increased.  Yet again, this bitch did have an infection - thought to have been picked up while walking in the local forests so anti-biotics were required.  So although it did cost more than I thought, I am still pleased I went ahead and had it done to ensure she will have a healthy litter.

how soon before season is due do you get her swabbed as you know these girls will come in when it suits so not always prepared

I have them swabbed as soon as they start to show a coloured discharge - usually a couple of days before they show red.  By the time the results get back - you normally still have time to complete the course of anti-biotics if required.

yes I was advised by my mentor to swab as soon as she starts her season, then if she needs Antibiotics then you should at least get a week before mating starts.
My vets do give a mild Antibiotics on the day of swab just in case.

how long before do you need to give the CHV injection