I am brewing for the first time. It is a Chinook IPA. The yeast that came with the kit is Safale US-05. I brewed and pitched it on July 4th in the afternoon. The primary fermentation time is 2 weeks as per instructions.
Though the instructions have a temperature range mentioned against the yeast - I didn't realize that this is the ambient temperature range I need to maintain while fermentation takes place. I learnt later in the night that it's better to maintain a temperature between 62F and 70F and anything above 72 risks esters and off flavors. I checked the fermometer on the side of carboy in the night and it read 76F-78F. Yikes! I immediately wrapped a couple of wet shirts around the carboy and turned up my AC and that brought it down to 74-75. Then I ordered an insulation bag for the carboy into which I can put ice packs and bottles that will bring the temperature down to range I need. The bag won't arrive till tomorrow - July 6th. My question is- 1) when is the most important time for fermentation? Am I already too late? I already have a thick Krausen within 18 hours of pitching.
2) will bringing the temperature down now control the hot alcohol / off flavors?
Also, I didn't check the temperature when I pitched the yeast. I'm quite sure it wasnt too warm because I had cooled my wort down in a water bath and added cold water to the carboy + cold water on top to bring the water level up - the tap water is quite cold even in summer where I live. I have a robust fermentation going with constant bubbles in the airlock and a 1.5 inch krausen already.