When to expect eggs back, after a break?

I have no eggs at all at the moment! I actually had to buy some at Tesco, for the first time in 3 years.    I had a bit of a situation last month with red mites, which was unfortunately made worse by leaving my mum in charge for a couple of weeks while I was at work. During this time the hens stopped laying, and after a really enormous argument with my mum she stomped off with her motley collection of chickens and I was left with an infested henhouse, and not quite enough hens for the amount of mites I clearly had now. After a monumental battle, involving every kind of chemical and barrier offensive known to poultry-dom, I am now free of the dreaded creatures.

(Honestly, I have never had them in 3 years. I work abroad a bit, I left my mum in charge, and after a week or so she told me I was not getting so many eggs. While I was home I checked in on them, and was horrified to find the mites, set my mum up with bucket-loads of Diatom, vaseline, and permethrin spray for spraying in the nooks and crannies. Next time I was home and opened the hen house door waves of them came out at me and I had them crawling on me all night. I was aghast that they That was when they could multiply so much when my mum was spraying them nightly with mite-napalm. I asked her if she needed a new bottle of the stuff any time soon, and that was when she sheepishly told me she was waiting for me to finish my line of work, as she couldn't see the mites without her glasses on. That was when the poo hit the fan, as she had been telling me she WAS spraying the house. And what was wrong with putting her glasses on anyway? I had thought my mum might be a bit better at looking after them than my husband, who let the fox in the pen then only time he was left in charge!)

So, after complete familial breakdown, I was free from work with enough time to attack them myself. And sure enough, repeated nightly spraying eracicated them after a not too long timescale.

This was about 2 weeks ago. Now, however, I still have no eggs. I've been giving the hens Battle's liquid in their water, as it says it has a good amount of iron in it and is suitable for hens recovering from mite infestation. They are workmed regularly, and although a few of them are currently moulting, at least 3 or 4 of them ought to be giving me eggs.

Does anyone have any idea how long I can expect to wait before the hens are feelign back to their normal selves and laying as well as they were again? Because I am sure the eggs from Tesco won't be as good as my hens'.

They are all between 6 months and 18 months old.

Typically, when I got back from the shops with my inferior eggs (thin shell, watery white, pale yolk - yuk. But my little girl was clamouring for EGG for dinner!) there was a lovely big creamy-coloured egg sitting there in the nest box. One of the Sussex, I suspect.