Since I have pullets that I want to live with the flock before they start laying, should I get the all flock and provide calcium separately, and then switch to layer feed when they are all laying?
Also, my pullets are about 5 weeks old, how old do they need to be in order to live with the rest of the flock? They have been in a separate run right next to the big girls for 1-2 weeks now.
You are going to get various answers to both those questions, the correct one is the one that works for you.
I, and many others here on BYC, follow the "
All Flock All the Time" feed management method (with free choice oyster shell, fresh clean water, and grit [if required]). I almost always have hatchlings/adolescents about, plenty of Roos, and free range - so its the only practical feed management method for me.
If you have an all female flock of production hens, once they are laying, or they are all very near to laying, you can transition to a "Layer" type formulation to save costs. Some then go back to All Flock (or a specialized Layer, like Nutrena's "Feather Fixer") to up protein levels during molts and speed that process along. Most don't.
Again, not wrong, if those few $ savings matter to you and its convenient not to have a separate calcium source.
When to integrate will get a LOT of opinions. Many will have successfully integrated already, often they use broodies for their hatching, and the chicks stay w/ broody mom as part of the flock from the start. I free range, I've had a lot of losses that way - primarily crush injuries from other animals, NOT predation (though some of that, too). I keep mine separate but visible, and on a different feed regimen until somewhere between 7 and 12 weeks (based mostly on when I have time to send birds to freezer camp) - that works for my unique management. Others keep them separate, and on separate feeds, until they are about to lay (14+ weeks, depending on breed averages) then integrate and feed transition at the same time.
Again, best answer is the one that works for you. No "one right way", plenty of wrong ones.