When can/should I next bleach my hair? What vol should I use?

For a cool toned light silver you will need a light blonde base.
It is up to you whether to continue bleach bathing or go for a full head bleach. How much lift are you getting from the bleach baths? How is the condition of your hair?
If you go for a full bleach you should wait a week after the last bleach bath, but then you will need to wait at least a month before any further processing. On hair that is already processed 20 vol should be enough to get from a gingery blonde to a light blonde with a good bleach powder. You could then bleach bath to even it up in a month if needed.

My hair condition is still in very good condition. I've been using only sulphate/silicone free shampoo/Condtioner, protein/moisture treatments and coconut oil. So my hair still feels quite soft and moisturised and I can't really see any noticeable damage.
If I can do a full bleach in a weeks time I might do that and bleach bath again in a month if I need. Next weekend I can get a friend to help me which will be a lot easier than having to bleach bath it every week myself.
The first time I bleach bathed my hair, the bits framing my face went blonde straightaway, but that was probably because I put those bits in foil. The rest of my hair has been lifting kind of slower but maybe I should have put them in foil or at least stuck a shower cap on (I did this the last BB for the last 15 mins and used the hairdryer for a couple of mins). Also the back of my hair has been lifting slower, but I think that's because I couldn't do it myself so easily.

I normally wrap a plastic bag over my head followed by a towel to keep my hair warm and stop the bleach from dying out. I used to always have random bits at the back that wouldn't lift as well but doing this really helped. I only get bad lift now if I actually manage not to get bleach somewhere. Otherwise it sounds like you have a good plan 🙂 good luck.

Thank you! I think the plastic cap and towel sounds like a very good idea. 🙂 I'll give it a go

The hair framing your face tends to be finer and lighter too, the back of your head generally has thicker and darker strands that are more resistant to bleach. Now the weather s colder it is important to do the bleaching in a heated room too, it makes a huge difference.

Thanks for the tip! I didn't think about that.

Do you think I should with start on the darkest parts first and the ends and then work up to the roots so it lifts evenly? When I bleach bathed my hair before I did the back/insides of my hair and roots last so it would look darker there and more natural, but for something really light like silver it would probably look weird if the colour wasn't even.

Yeah that's usually best if you're trying to get an even colour. It's hard to do on your own though (well for me anyway :p) so enlist someone to help you if you can 🙂

Okay cool thank you! 😛 I'm deffo getting a friend's help

For silver you need it to be pale blonde, leaving it darker will mean more oarnge tones which will turn silver dye to ash blonde rather than a darker shade of silver. Your plan of starting with the darkest parts and doing the roots last is good, remember to do a strand test so you have an idea about timing. If you want a darker silver at the roots you can create that by mixing dyes once you have your pale yellow even base.

Thank you very much! Mixing more silver for darker roots sounds good