These guesses like "you will get PPR within four weeks after AiP" and the like were mostly useless before anyway, because they usually came from a handful of specific experiences without accounting for which visa office or any other factor.
But people really want to hear a number, even if mostly fabricated, so not worth fighting it.
Congratulations on reaching the first stage approval! This approval confirms your eligibility as a sponsor and the genuineness of your relationship.
Next Steps is Background & Security Checks on your partner, Medical Examination to meet health requirements and Final Decision on the permanent residence application Processing Times: Generally, it takes about 10 months for inland applications and 13 months for outland applications. You can learn more about First stage approval for spousal sponsorship here.