Is there any evidence to indicate when - what year by our Earthly reckoning - the Time Lock was put in place around the Time War between the Daleks and Time Lords?
There isn't any real answer to this question, as it implies that the Time Lock somehow exists within what humans conceive of as "linear time". Once it had been put in place, the Time Lock "always existed" and "will always exist". The events of the war were removed from the flow of time itself. That's one of the problems with using human language to discuss concepts like time travel that our minds aren't built to comprehend.
The closest we can really come if to look at it from the perspective of someone that was "aware" of Gallifrey and the Time Lords but did not participate in the Time War itself, and thus would have been observing from the outside. Any of The Doctor's companions that were still living on Earth at the time would qualify, e.g. Sarah Jane Smith.
From their perspective, in 2000, the Time War had not happened yet. The 8th Doctor was on Earth in 1999 (the events of the Doctor Who movie), pre-War, in conflict with The Master. He leaves Earth on January 1, 2000. By 2005, the Time War was over; The Ninth Doctor meets Rose Tyler on March 4, 2005, having recently escaped the Time War and regenerated.
So, from the perspective of someone living on Earth during that period, the events of the Time War and subsequent Time Lock happened at some point between 2000-01-01 and 2005-03-04.