All the player contracts end on 30/6/2020.
All the coaching staff contracts end on 30/6/2020.
The 1921 end of year is 30/6/2020.
The Holdings end of year is 30/6/2020.
The EFL season officially ends at the close of the AGM, held on (or the nearest practical earlier date to) 30/6/2020.

Perhaps the best takeover time should be based upon this date. In order for this to occur maybe the practicalities will begin at the beginning of June in order to be completed promptly and to have the team management, coaching and some new professional playing staff on board in time for pre-season training and friendlies in July. Of course contracts beginning at the start of July can be signed before that date, possibly at the beginning of June.