First time homeowner: Lawn care question

Hi all,

Got first house a few months ago and I am going to try to follow Randy Lemmon's lawn care schedule posted here: https://randylemmon.com/lawns/randys-lawn-care-schedule/

The schedule says to put pre-emergent in October but doesn't mention exactly when in October. I heard it's usually according to the soil temps. Does anyone know what's a good week in general to put pre-emergent or it varies each year depending on soil temps? What's the desired soil temps that qualifies the application of pre-emergent?

Thank you!