Martin Lewis said prices are going down by an average of 17%.
If you are planning to do something that will use a lot of energy between today, 1 July and your next meter reading date, e.g. mowing a big overgrown lawn, hedge trimming, binge-watching six series of a TV show, batch cooking to fill the freezer, and you haven't sent in a reading, usage will be averaged over the billing period and you will end up paying for some of those units at the old higher rate.
If you are planning to be away from home sometime between now and your next reading date, averaging will work in your favour.
If your usage over the month is consistent it shouldn’t make a great deal of difference but it’s worth sending in a reading now if you want your bill to be as accurate as possible and it will help to budget for coming months.
My reading date is the 8th of the month. I sent a reading yesterday 30 June. My next bill will show me what 8 days at the new rate has cost so that will give me a good indicator of what my ongoing monthly bills will be.
I don't want a smart meter for various reasons but this is one of those times when it would be good to have one.