Awesome info!! Now I live up north in NH, not quite as warm and humid as your locale. Now I was wondering about doing this regime as a preventative measure, as none of my flock have worms. Would it be good as such or only if I saw signs?? Also it seems you eat the eggs no problem, do you still wait for the withdrawl time or no?
You have to seriously take your environment into consideration as to how often you should worm your birds, especially soil conditions.
Where you live, I suspect your soil is cool, cold or frozen most of the time. Unlike our soil, just the opposite. REMEMBER, this is for folks who live in the northern states where the soil is practically frozen tundra most of the year LOL.
I think it would be in your best interest to gather multiple fresh fecal samples and place them in a ziplock bag. Then take them to a vet for a look/see under a microscope. The vet will let you know if there are any worm eggs, then you can treat accordingly.
There's a very good chance the microscopic slide will be free of worm eggs and you will have saved money of not having to purchase a wormer.
However if you still feel that you must worm your birds, just before springtime is best or just before birds are at point of lay in the spring.
Withdrawal times are the times you toss eggs in the garbage due to residue in the eggs. It's your choice whether or not to eat eggs containing wormer residue, however slight it might be. With most wormers, there is no set in stone withdrawal periods. Some companies state that eggs can never be eaten again, Wazine was a prime example. However the company DID state there was a 14 day slaughter withdrawal.
Another example is Ivermectin. People to this day still use it in their birds. I've used it long ago but dont anymore for two reasons; it has lost its effectiveness as a wormer in poultry due to overuse as a miteacide in poultry. Large roundworms are resistant to the product and I dont care what anyone says about it. This is from my personal experience as well as other chicken keepers I know.
The second reason why I dont use it is due to the long withdrawal period, 30 days for Ivermectin pour on. This is one of the wormers that I tossed eggs in the garbage for sure. Another is Eprinex, even though there wasnt a withdrawal period.
The company that produces Ivermectin and Eprinex, Merial, simply states that Ivermectin and Eprinex are not for use in poultry.
That said, there are other certain wormers that I'd definitely toss in the garbage as well. But I havnt used them in years.
IMO The Benzimidazoles are the safest wormers on the market for poultry which includes Fenbendazole (Safeguard), Albendazole (Valbazen), Flubendazole (flubenvet), and others.
I hope this helps.