What we've found useful in terms of time estimation is MPST (minimal possible subtask) and TV (task visualization). For each task, divide it up into the smallest possible subtasks by visualizing the process of how you will do them, consulting them as necessary. Then, label each subtask with how much time you think it will take, and cross reference your progress so far to see whether it matches up. Add up the hours and that is a better estimate of how long your work will really take.