Hello Vincent,
First of all you need to have hot gate otherwise you cannot control the timmings.
What you should do is create a beam element with 1mm of high (for example) and edit the properties putting as hot gate with the diameter you want.
After that, when you go to the properties of this element you will see that there is a board and one of the tabs is "Valve gate control". Here you can control how you will fill the part.
If you have more doubts, send another post.
Best regards,
Gonçalo Rodrigues
MOLIPOREX
Portugal