They are leading you in the right direction. An average of 8 weeks then take them off the starter or finish up what you had and as you say, none left. From here you can go to poultry grower mash or lay mash. Pellets are pretty big even for 8 week olds in my books and having to crush up pellets is a pain...
I would go with grower mash first and after they start laying you can switch over to lay mash or continue with grower mash for a while longer Having as many birds as I do I use 3 mixes and combine as I see fit. I use grower mash,pellets and scratch, equal amounts of each.Some chickens get fussy with one feed but have the option of the other two feeds and all are satisfied.
That can be expensive in the long run so go with the grower mash. Others here may suggest a different regiment but I stick with what works... spoiled birds.... Have fun, your girls are at an interesting stage and the cutest stage in my books. Steve