Time Study Sheet

This time I am planning to prepare a "Time study sheet" for my team.
I need to apply a few conditions in it to make it more effective.

1) In this what I have done is put a data validation in “C”

Condition needs to be added:-For the first activity I wanted to add the condition like “First I need to choose the activity then only I can enter the Start time or else dialog box should pop up with “Choose the activity first”.

2) I already put the macro in Timer button, so once I Select the “Start time” column and hit the button, the current time will reflect, and after that, once I Select “End Time” and hit again the Timer Button Current time will reflect.

The first Condition needs to be added: - For the second activity Start time should automatically generate when I am selecting the “End Time” for the first activity, and this should continue for all activity.

The second Condition need to be added:- Here I want is, By mistake if I hit the Timer button except selecting the “Start time” and “End Time” popup should reflect “Select appropriate line “

The third Condition needs to be added:-Until and unless I close the previous activity by selecting the “End Time” I should not allow to start the next activity.

After all the above C4: F43 should be no editable fields, Once we entered the activity or time we should not be allowed to edit it.

It will be a great help if anyone can help me to put all the above condition in the attached excel.

Regards
ArindamTime Study.xlsx

Not getting any update on this..can anyone help me out in any of the conditions..