Estimates are shown in MyProgress. Sometimes it's visible, some times it's not.
What I can tell you for sure - it's never accurate.
My estimate showed "3 weeks until decision" on the day I became a US citizen!
Here's official processing times:
https://egov.uscis.gov/processing-times/
You can search based on your field office location.
Again, when I filed N-400 my office showed 7 months, but my case got approved in 3.5 months. But for some filers, it will take longer than estimate. In general, I recommend to be morally prepared for 9-12 months of processing.