Help!/Series Pages

I'm reposting this here. I accidentally posted it in the wrong section a few hours ago.

I was wondering when series pages are allowed to be created. Looking back TW and the SJA, series 1 pages were created quite a while after the premiere episodes, but with K9 the Series 1 (K9) was created in June 2009, months before Regeneration broadcast. I know we create series pages before the series starts (such as Series 9 (Doctor Who 2005) being created a month before the broadcast of Last Christmas), but do we also create series pages before the premiere episode of a series has begun? If so, how long before?