I'd like to share my Google Calendar with a colleague, giving him access to view/read all event details which aren't set to Private.
Can I specify that he only be allowed to view events starting 01-01-2016 and into the future, but none of the events before that date?
No, I'm afraid not. If you're going to share a calendar, the whole calendar gets shared.
The only thing I can think to do to perhaps create a second calendar that you can move all of your old events to. Bulk-moving events from one calendar to another is not an insignificant problem, though.
Alternatively, you can create a second calendar and share that with your colleague. You'll just need to remember to add the events that you want to share to that calendar.
