The confusion comes in a large part bcause so many different things work. You are fine. You can start feeding that combined Starter/Grower now and keep feeding it to them until you switch to Layer.
I'll start with the basic progression. The "standard" method is to feed them Starter (which should be around 22% to 24% protein) from hatch until somewhere between 4 and 8 weeks old. Then you switch to a 16% Grower and feed that until you switch to 16% Layer. The only significant difference in Grower and Layer is the percent calcium. You should not feed excess calcium to growing chicks. It can damage their internal organs.
I can't do the "basic". My
TSC does not carry all those feeds. But what they do carry is a 20% combined Starter/Grower. You can feed that 20% Starter/Grower from hatch until you switch to Layer. That's what is is made for.
There is another option. At about 13 weeks, you can switch to a 15% Developer, or maybe 15% Grower/Developer, and feed that until you switch to Layer. Or switch to a 16% grower.
There is another option. You can feed them a 20% Flock Raiser from hatch until you switch to Layer.
Or you can make up your own sequence. It is not that critical. The general idea is to give them a fairly high protein feed until they feather out, which is usually around 5 weeks. Then you can cut back to a lower protein feed which is enough to keep them growing and developing on schedule.
Normally you switch to Layer when they start to lay or around 20 weeks old. If they start laying earlier than 20 weeks, Layer is fine. If they don't start laying until well after 20 weeks, you can keep feeding them Grower or Flock Raiser if you wish. It really does not matter.
Even after they start to lay, you can keep feeding them Grower or Flock Raiser and offer oyster shell on the side. You don't have to switch to Layer, but they do need extra calcium for the egg shells.
I only have two rules on what to feed them. The most important is to not feed them excess calcium until they are 20 weeks old or they start to lay. My second rule is to not feed them exceedingly high levels of protein, especially after they are maybe 8 weeks old. To betterr define exceeedingly high levels of protein, I've seen studies where feeding them over 30% protein feed can cause some medical problems. So whenever the bag of feed runs out somewhere between 4 and 8 weeks of age, I make sure I don't feed them anything higher than 20% protein. But I have no problem feeding them a 20% protein feed. And that gives me a lot of options.
The question of whether or not chicken feed has grit comes up a lot on here. It is not on the ingredients list, so I e-mailed Purina and asked them. Purina chicken feed does not have any grit added.
As long as all they eat is the processed chicken feed, they do not need grit. The way the chicken feed is made, the major companies grind up all he ingredients and form it into pellets or crumbles with water. Or they just leave it as mash. There are no nutritional differences in mash, crumbles, or pellets. The different forms of the feed are just suited to different mechanical feeding systems. Note I said major companies. Some local mills may make their own chicken feed. Chickens may need grit with that.
Since the feed has already been ground up, the chicken's gizzard can grind up those pellets or crumbles without any problem. If you want to feed them anything other than chicken feed, like grass, greens, or grains, they need grit. How much is hard to say but not a whole lot. I just take some sandy soil from my run and put that into the brooder. You can sometimes find chick grit or even just give them some coarse sand, like construction sand, or even scrape some small rocks up from a gravel driveway. One word of warning. You can get parakeet grit at a lot of pet shops, but read the label. A lot of those have calcium added. Remember, excess calcium is bad for growing chicks.
