Milk coming in…or not getting out? Engorgement at day 3

About milk coming in on day 3. A discussion in a closed group prompted this.
People need to realise that milk coming in is a gradual process, from about 20-48 hours onwards, as progesterone levels drop and lactose synthesis revs up, and with it, an increase in milk supply.
Stasis can occur when there is a combination of venous engorgement (from increased blood flow to the breast bringing nutrients for milk-making), and the actual increased milk production.
So if milk is removed as efficiently as twins do, no major changes may be evident: the venous congestion is not blocking milk outflow and milk is not stopping resolution of the venous engorgement (which is, like swelling anywhere, responsive to cold forcing fluid back into the lymphatic system). Warmth expands and allows milk outflow, cold contracts and reduces oedema. So warmth and cold can both be good, but you use them knowing what they do when.
As I said to health professional students I taught for decades, that full bursting double XX painful breast engorgement is a sign NOT that milk is coming in, but that milk is not getting out, and lymph is not draining well!
AND in well-managed mums it should be rare, if midwives know their job and can do it because adequately staffed.
There can be delays in the process of milk synthesis if progesterone hangs around due to retained placental fragments in utero, or due to metabolic issue like diabetes -which delays it by a couple of days at times, but diabetics need to breastfeed to improve their own control as well as to reduce the baby’s risk of later diabetes.
Those delays in milk synthesis sometimes make the use of expressed colostrum or donor milk necessary, but all artificial feeds should be avoided.