I suspect that, if she lays at all in a year, it would be around this time through late April. I call it the 'spring flush', and generally late Feb./early March through late April is when I see my older girls lay. That said - while I shouldn't have girls that old, I have 10 that range from 5-6. They are either my 'special' girls, or ones that are good broodies, so they get to stay.
I think she is starting a bit early - but then you are also much more Southerly (latitude wise) than I, so I am sure that makes a big difference.
Also, if I remember correctly,
@RebeccaBoyd 's 'Ole Bat' is around 10 and still laying...and hatching/brooding chicks. Granted, she takes quite a bit of time off each year from laying due to her broody nature - meaning she isn't 'using up' her given egg supply in a rush like the Leghorns, but they will continue to lay as long as they have 'eggs' (i.e. yolks) left to produce and are healthy enough. Just don't expect her to lay like she did at 3 years of age. Fewer eggs, maybe thinner shells, and most likely thinner/less viscous, whites. Still good to eat, as long a shell is intact, though!!
@BY Bob might be able to add to this comment. Mine is based solely from my limited experience - Bob has more experience AND more education regarding chickens.