Currently I use grains acquired from feed mill but used to be that we raised. Soaked oats for me means oats have been immersed in water for at least 24 hours at roughly cellar temperature. It can go longer to point of fermentation but my preference is not to let it go that long. I make so multiple 5-gallon buckets tied up so a given batch is no more than 72 hours old.
What I do to simply things is to use the same base formulation of known quality ingredients all winter long. It is applied at a rate that keeps bird in constant weight when fall temperatures are mild. As temperature drops and feed consumption increases I also begin to increase the application of the whole grains such that virtually all is consumed by dark. This means I pass each pen 3X daily . First time in early AM to apply base formulation, second to check for feeding interest with application of the whole grains and a third about dark which can be very shortly after second pass to assess consumption of the whole grains. I want birds on roost with obviously distended crops but little or no uneaten feed on the ground at the end of the day. I have to problems with uneaten feed on the ground at night; first is it provides food pests such as rodents, and secondly because it can be an additional attractant for predators such as oppossums and raccoons.
If you are using the gamebird feeds I am familiar with, then their application sets up for increasing protein intake at the same time you are increasing the overall energy intake. My birds have it too rough to get by on layer formulations when using additional whole grains as energy source. Regardless, you will have find out how your birds respond based on trial and error. If they are are in lay then you have a pretty sensitive indicator to follow. For me I have to watch the birds closely and even make adjustments based on weather. It is not as easy as simply providing a formulated diet in excess so you will need to weigh benefits and costs of each approach. I am management intensive which makes my thinking particular to that.