well i would do a five day thing. it either can be very intense or medium depending on how your body works. you probably want to build some endurance for the first few weeks.
so for a few weeks i would do
m150m sprints@60% of 200mx6
tues:general day:warm ups, strides, ect ect
wed: speed:20s, 30s, 40s try 4x20, 2-3x30, 2x40
thurs:general day
fri:100 sprint, 100jog, 100, sprint, 100 jog. you want this at 60-70% keeping form. adjust job to get your breathe. do 2-4 sets in 400-800m each set.
that would build endurance to get the legs ready for something more intense as far as speed work. i would do that for two weeks.
then you can drop one of the enduance speed days and do 20s, 30s, 40s. 20, 40, 60, 80, 100. it all depends.
you also could do ladders which will get u into shape and is quick and will be a faster alternative to long and shitty cardio.