Is it literally at the beginning of your turn (before 1.1 in the timing diagram) or during the Turn Begins step (1.2)?
The FAQ 1.0 updated the timing structures and now it says:
1.2 Turn begins (“When your turn begins” conditionals meet their trigger conditions)
The FAQ 1.0 also says this
a player only replaces recurring credits up to the number
listed on the card when his or her turn begins.
So, the answer to your question is 1.2