When did it start?

According to Google, they first started investigating the issue in the early morning at 1:2 AM ET. Their current statement on the issue:

When did it start?Downdetector showing spikes

 

Downdetector showing spikes

According to the real-time outage and monitoring service Downdetector, Google products such as Gmail, Drive first started showing disruption at around 11:57 PM of the last night.  Some YouTubers are experiencing issues in uploading their videos to the channels as well. Watch this space as the story develops.