when do royal mint releases generally go on sale?

when the 4th coin in the 2020 tower of london series went on sale, I got an email at 426a central us time - does that mean royal mint releases generally occur at 10a gmt?
anyone with knowledge of / experience with this, please chime in
thx ✌
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no one knows? just bumping to make sure - thx for any help
fwiw - seems like they go on sale 0900 GMT ✌