Right off in the morning is your official weight. After you pee, before you drink coffee or poop. That’s the weight of record.
Right before your fast ends, after exercise, thirsty and sweaty, etc…that’s your dream weight. That’s where you are headed that week. But once you eat and drink, that number is gone for the day.
Also, don’t drive yourself crazy.
I’m after the lowest weight for the day, anything else would be just pure randomness as I don’t track every calorie and gram ingested and excreted over every second of the day. Given that I don’t do extended or dry fasts and that by the time I’ve left my bed and have visited the bathroom it’s been 0 hours since my last bladder emptying, 8 hours since my last sip of water and typically 15+ since my last meal, that’s the only reasonable choice, i.e. the only time of the day at which the measurement conditions are somewhat stable.
I don’t think it really matters as long as you are consistent so you have a baseline for comparison. Wear the same clothes as well to help with this. (Underwear maybe)
I get weighed all the time for other medical reasons and I’ve yet to find any two scales agreeing with one another. I mean expensive hospital ones as well. My GP’s also give a different result.
It could be your home scales are out by 5kg for example but it doesn’t matter as long as you use the same ones at the same time in the same clothes.
I’d also suggest it doesn’t matter though anyway if you see the results then that’s all that matters
Always after my morning poo :) but if you keep it consistent you’ll catch the swings before they get too big and celebrate the dips. I’m in maintenance mode but I just moved across the country so I’m starting to really learn what makes my body hold weight, shocking, wine and sugar.