So, when I lived in another part of the world that was colder long ago I'd make these little ghetto heaters- heat bombs ? it was a fish tank heater in a bottle I'm pretty sure, it radiates heat instead of heating a surface like your mat. You're probably good on temps, I should have asked where you live, we've got snow in some places, i wore shorts today though where I am... I'd check the room temp- you don't want to heat the bottom only, but shit if it's working let it ride.
Things I write in a grow log- the obvious shit- strain, spawn, substrate, date innoculated, date of full colonization, date of substrate innoculation, quantities of all things used in sub and spawn etc. stuff like that. do you have a hygrometer/thermometer? get one of the little electric ones and put it IN the tub, if you can get one that marks the high/low temp over the day and the RH swings through the day that's what you want- its nice to know how stable (or unstable) the atmosphere is in your chamber, and just a regular ol' thermostat to put in whatever area you colonize your shit.
I also write down shit I notice that may or may not be helpful later, growth patterns, any weird things your mushies are doing as they mature (are the caps getting a split look?' is it throwing all big clusters? anything.) RH is a big one in the tub. dry sides generally mean there isn't a high enough RH, which can be more of a battle in the winter with generally dry air.
Write down the dates, wet and cold weights for all harvests. Its good to know if that strain throws monsters in later flushes or if it shits out after 1.
It will also be a guide to growing a particular strain, some like different substrates, different spawns, some colonize slower, etc... you might think you'll remember all the little things, but you won't. The goal is always to get the environment completely dialed in and by looking back at successive grows and seeing what variables changed you can get a real good idea of what perfect is to these mushies.
One variable that I like: bio efficiency- this shows you how efficient your myc was at turning food into fun. Take your DRY substrate weight, divide by the WET weight of all your flushes, and multiply by 100%. I know it sounds weird not using the weight of your whole substrate after hydration but using wet mushroom weight, but I didn't make it up. Ideally, you want 100% BE and since you're measuring wet vs. dry you can get OVER 100% bioefficiency and thats just how it is. It is a common # used in commercial applications with non trippy mushrooms and we don't really need it- what's a lb of mushrooms cost to grow ? 10 bucks? but if you're growing edibles it's a great overall indicator on how dialed in you REALLY are vs what you THINK you are. Missing 10-15% of the energy you put into oysters is a big deal to commercial growers, margins aren't huge in the edible business and they are very serious about their operations.
If anyone else has anything good to add in. post it up