Any advice saying take half is incorrect.
The BMS has a guide on endometrial protection with HRT and it's the same dose as orally.
You can actually insert it at any time. (I asked my consultant this. It's also used for fertility 3 times a day .)
The use at night is for oral use, as it can cause dizziness or sedation, but this doesn't apply to vaginal use.
Obviously if you do use it vaginally during the day, maybe have a trial to see how you react.
The important thing is it stays where it is put as it can take up to an hour to dissolve.
You will get some residue and even some discharge, so panty liners are the way to go!
If you use it at night, just do it lying down, last thing.
You can't really have sex once it's inserted but you could use it afterwards.