What age did you start a routine?

[beckieperk]

Just that really. With ds1 we established a bath, bottle (whilst In the Night Garden was on) and bed routine and stuck to it as much as possible. But I can't remember what age he was when we started.
How old were your dc when you started a routine? And do you have any top tips? I've forgotten everything!! Thanks in advance.

Probably properly when they started preschool at 3. Or possibly when they dropped a morning nap and would reliably have a nap after lunch but I can't remember the age for that.