Immigrationboards.com

I keep getting conflicting answers.

Most people seem to have submitted (and paid for) their Citizenship application and had their Biometrics appointment a few days later. In my case, I had my Biometrics appointment a whole month after submitting my application.

So the question is: does the timeline begin once you submit and pay for the application? Or does it start after you have your Biometrics appointment?

Thank you!

This is not entirely clear yet - technically the documents are submitted at the biometrics appointment but some applications seem to get processed rather quickly so it is not obvious how exactly UKVI assesses applications. The standard processing times are of 6 months for naturalisation applications. I also had my biometrics appointment 4 weeks after applying and received my approval roughly 4 months after having applied.

I would say it is from the application date. They have enough information to start working on the application.
There is no benefit to paying for a biometrics appointment, so you don't need to worry that yours is later.

I say this as I have seen a few cases where people have delayed their biometrics appointment until the last possible time. Their applications were approved within a week or 2 of this, therefore taking the same amount of time as if they'd had their appointment straight away.