Calculation of average time between two levels

Hi Team,
Thanks for the help in the past.You guys are just awesome.
Could you please help me in this new issue.
I have my dataset as shown below :

Scenario is this is an orders table. Each order(e.g 2000)  includes multiple sub-orders(e.g 111,222 etc) as mentioned above.Similarly Order 3000 has placed multiple sub orders.
Each of these Sub orders travel through various levels (M1,M6,M2 etc) and users update these sub orders. The raised and changed date are updated as they move from one level to another.
Now I need to calculate
Point 1:
average time spent for all orders (keeping track of Sub orders too) in each of the level e.g
1)Average time spent by all orders  from Level 1(M1) to Level 3 (M3) or
2)Average time spent from Level 3(M3) to Level4(M4) or time average calculation between any two levels.

Point 2:
Average time spent by orders in each of the levels(M1, M2,LM etc) i.e If I select M1 in Slicer,it should give me an average time  for all the orders spent in M1 and respectively M2,M3 etc
I used the Earlier function for the second point and I guess it worked.
Any other fool proof solution would be appreciated.

Thanks in advance.