Building on the question "move from estimate to billable" from Matthew.Stanfield on Feb 27.
In the right click drop-down menu in the Work tab, add an additional choice, Convert Estimated to Working Debt/Credit. This choice would be a combination of the following actions:
1. Duplicate the selected Debt/Credit(s).
2. Convert the duplicate Debt/Credit(s) from Estimated to Billable.
3. Reset the hours/quantity value to zero.
4. Set the Date to "today."
This could provide a viable way of changing estimated items to working items while retaining the estimates as suggested by Matthew's question. Actually starting timers has been left out of this suggestion because converting a quanity of estimates to working wouldn't necessarily warrant starting all of the timers converted.