It depends on what kind of part time you go for. There are a few options. "Right to request" and "Aspirational". And then there are different options within those.
Standing by to be corrected, but:
- Aspirational (I want it): You bid for this annually and you "might" get it. Not sure how long this takes
- Right to request (I need it): Normally within 9 to 12 months (depending on which fleet you're on and if they have enough pilots to cover the work)
I've requested the RTR version recently for childcare and have been told to expect a result next year.
edit: “Just to clarify for people wondering after NLP’s comments, Right to Request can now be for any reason/person, it is not the sole preserve of parents.” (Thanks Rex)