The winter pause
You purchased some hatchlings in spring—hatched in-season. They are now more than 22 weeks old so they should be laying right? But they are not, or only sporadically. There is nothing wrong—its autumn. An often overlooked aspect of backyard chicken keeping is how day length affects laying. Hens generally need at least 14 hours of daylight to lay well [1-3], but in Melbourne about 14 hours day length is achieved only from Nov-Feb (see table at bottom). So your pullets—now becoming hens, may not start laying until spring, when they are almost a year old.
When to buy chickens
Because of the winter pause the best time to buy point-of-lay colour-sexed browns (CSBs) is spring. You can source these any time of year because the chicks are bred by a small number of large primary hatcheries operating year-round, e.g. Specialised Breeders Australia in Rochester, Victoria, is a primary breeder of Hy-Line and Lohmann Browns. These hybrids are sold to secondary vendors for use in their own layer farm or for sale. Alternatively, source younger pullets so they will be 22 weeks by spring. There are several secondary vendors for the CSBs, as listed under WHERE. Typically a point-of-lay pullet acquired in spring will start laying within a few weeks and keep laying to autumn. It will then go off the lay, moult, and resume laying again next spring, etc. It is not possible to follow this schedule with breeds because they come from smaller suppliers which generally hatch their chicks in-season.
Getting around the winter pause
To get around the winter pause, you can provide your birds with add-on lighting in the morning to achieve 15-16 hours effective day length (see table at bottom). Add-on lighting is a simple and cost-effective way to maximize your egg production. It achieves two things: (1) allows your hens to start laying when they reach 5-6 months of age regardless of season, and (2) promotes peak laying for longer periods of the year so you can reach that 300 eggs per year target. Some think prolonged laying forced by add-on lighting is not good for the hens, but I have yet to see or read good evidence. Laying an egg is a natural bodily function for the hen, and if they are well fed and looking good, then....?
Add-on lighting is applied only in the morning because the hens require a natural sunset to give them time to settle into their roosts. Install a warm-white globe with a colour temperature of 2700-3000K . A 4W LED globe will provide enough light intensity for backyard coops: if you can read at floor level you have enough light . The cost of running this globe under the schedule outlined in the table below is negligible: $1.58 per year at 27 cents per kilowatt hour . The effect of the add-on light assumes the hens are exposed to it—if they leave the coop into an outdoor run where the light is less intense, there may be no effect.
With add-on lighting you can buy point-of-lay CSBs anytime, but around May is a good time if you are going with add-on light. When they are 18 weeks of age immediately increase the effective day length to 12.5 hours then add 30 min. per week until 15-16 hours is reached. This schedule approximates what is done in the layer industry  although an abrupt transfer to 14 hours at 18 weeks also works well .
Your hens typically will moult when they reach 18 months of age . If they were acquired at point-of-lay in May, then 18 months of age will be about April the following year after about 10 months of laying. To provide an opportunity for moulting, do not provide add-on light after summer into the autumn. As the day length continues to shorten your hens may drop back their laying and start to moult. This is variable and unpredictable—hybrids and some breeds might continue laying well despite the shortening days, and moult only gradually rather than suddenly. After the winter solstice in late June start to add back the light: set lights-on at 4.30 a.m. then move back 30 min. increments per week until 2.00 a.m. is reached. This will re-initiate laying in hens that have gone off the lay.
At the next autumn your hens will have been laying for two seasons, so its probably a good time to replace them. If you go for a third season you may not get enough eggs to justify feed cost.
1. Factors affecting egg production in backyard chicken flocks, Jacob et al. (1998) FactSheet PS-35, IFAS Extension, University of Florida, USA.
2. Lighting for small-scale flocks, Hawes R (2009), Bulletin #2227, Cooperative Extension Publications, The University of Maine, USA.
3. Understanding poultry lighting (2017), Hy-Line Technical Library.
4. Electricity Bill Calculator, RapidTables.
5. Lewis PD, A review of lighting for broiler breeders, British Poultry Science, 47: 393-404 (2006).
6. Lewis PD, Rearing photoperiod and abrupt versus gradual photostimulation for egg-type pullets, British Poultry Science, 48: 276-283 (2007).
7. Everything you need to know about molting chickens, Cybele D (2017), Wide Open Pets.