I guess if you use this product you need to do so when egg production is down. I found another wormer that doesn't effect you consuming eggs while being treated, but I haven't been able to find it here in US, just Canada. Thanks for your reply
If you've got a worm infestation, though, you should bite the bullet and treat, regardless of peak egg production. Worms can quickly kill off your chickens, ending any egg production.
If you're treating for worms just as a matter of course, you can wait until peak is over. My parasite strategy is to feed my hens raw garlic, once a week. Five hens, one huge or two medium garlic cloves, crushed well. Mix into a treat (like some moistened oatmeal with scrambled eggs, yogurt or cottage cheese) and feed to the birds. My girls REALLY love this treat, even more with the raw garlic. I don't taste any garlic or bad taste in their eggs. And it's safe to eat the eggs. Some people grind up raw pumpkin seeds and mix with some buttermilk or yogurt and feed to their birds on a regular basis - for parasite prevention. There are other organic methods, too, like food grade DE into the feed, etc.
Please note that what feathersnuggles is saying in the second paragraph is considered worm prevention - not cure. If your birds have worms, worm them with Wazine first to reduce the wormload. If that doesn't clear up the problem, try Ivermectin pour-on, applying a couple of drops to the skin on the back of the neck. For the term of treatment and 2 weeks following, feed the cooked eggs back to your chickens. If they have worms, they can use the nutritional boost.