I am in New Zealand and using Index Smart Scale and weigh myself in the mornings. However, when my weight uploads from the Index it shows in Garmin Connect and the app as relating to the day before. If I weigh myself after 1pm in the afternoon it uploads to the correct date. I have 2 watches and have re-set both of them and all settings are correct for my timezone (Auckland) except for daylight saving which is not accounted for.
There is a similar issue with my Forerunner 235 in that I have a Training Plan in my calendar which looks fine in Garmin Connect but in my watch the Training Calemdar has Sunday's long run under 'today' and my next relative day in my calendar is Wednesday 8 March 2017 with the Intervals I need to do on Tuesday, I am always missing a day?
Someone else who is in Australia has the same problem with their weights (see Timezone Funkiness post)