I’m a big fan of the Donald Reinertsen approach: measure queue length. Simply track the time to complete each task in the team queue on average, then multiply that by the number of tasks remaining in the queue. Each team will habitually slice things into sizes they feel are appropriate. Rather than investing time to try and fail at accurately estimating each one, simply update your average every time a task is complete. The bonus with this approach is that the sheer number of tasks in the queue will give you a leading indicator, rather than trailing indicators like velocity or cycle time.