Switching to a whole grain feed

Question I read this on the site of the food I am planning on changing my girls to:

" Use whole grain for 5% of the diet for the first two weeks to adapt the gizzard, then, over a couple of weeks more, increase the percentage to whatever level you have decided to feed. Birds fed whole grains have significantly larger gizzards. Grit needs to be provided at all times when the birds are not on pasture in order to help digest the whole grain."


My question is - I just was given these hens, along with some feed (typical layer crumble). I am going to be ordering a whole grain layer feed through Azure Standard, and it will not arrive until next week. There is just enough feed left to get us through until that arrives, but I will have little if any left to partially feed to do a "transition". What can I do? If it helps, with the current feed, and the new feed I have/will be doing fermented feed, each batch fermented 48 hours.

If i get some whole grain locally and mix it in for the next week, should that be long enough to transition?

Thank you!