I usually pitch my ale yeast after I get the yeast and wort both to my desired fermentation temp in the mid 60’s, but have read where other people pitch around 75-78* and then lower the fermenter temp to the mid 60’s AFTER fermentation has started. This seems to me that I might stress the yeast once they have become active at a higher temp, or possibly slow fementation down. Which way is correct?
Both ways work, but I get the best results cooling the wort to a couple degrees below where I want to ferment, then pitch and allow the beer to warm to the right temp.
I’d say that pitching warm then dropping the temperature is more risky.
If you get distracted and cannot be there to lower the temperature the fermentation may raise the temperature much higher than desired.
If you can watch it carefully, pitching warm will get the fermentation going quickly and actively.
It depends on the yeast and the ester profile you want. I pitch cooler than fermentation temperature whenever possible and let the yeast rise into fermentation range to keep the unwanted esters out to the extent possible. I also ferment on the colder side of all ranges (usually under the bottom of the manufacturer’s suggested fermentation range by a few degrees.) If you pitch enough yeast the cooler the better, but as with all things, YMMV, and ignore what I said if you are brewing a Belgian Ale.