Depending on the breed you have, some commence laying earlier – but is obviously dependent on temperature, daylight length, etc.
So, I’d recommend to commence feeding them laying pellets now – if it’s cold, add some
hot water to make a mash and mix in any vegetable peelings, they will virtually inhale this mixture because making eggs, feathers, and keeping body temperature regulated takes a lot of
energy.
As Marco and Mike advised, keep a container of shell grit freely available, otherwise the egg shells will be thin and, more importantly, it can strip their metabolism of calcium = weak bones = VERY serious as birds already have ‘aerated’ bone structures, so they can’t afford low calcium levels.