I have no experience working with football players, but I think from general stand point that tempo should have been introduced in the off-season and in-season…
You can put 1-2 tempo sessions /w but I think that this time should be used to develop strenght/speed characteristics…
When spliting team for tempo, it is bettet to split them according to their 100m time (or 200m), because tempo should be done <75% of this time.
Tempo progession could be based on increasing the volume of a run:
4x(100+100+100) 1st week (1200m)