The only advice is to do it properly. You need to decarb properly and you need to do the extraction or infusion properly. Do either incorrectly and you don't get much THC into your final product. I find decarbing a longer time at lower temperature to be more reliable/repeatable than a shorter time at higher temps. Cooking your edible can be done at any time. The heat of cooking does affect decarb so it somewhat depends on what you are making. Something that cooks for a short time like cookies doesn't matter too much. But, if making happy spaghetti sauce that might cook for long periods then you need to figure the food cooking into the decarb process so you don't over decarb and kill your THC. Butter is oil so it behaves very similar to other vegetable oils and can be handled interchangeably.