I often check every week for a while until I see that they are clear. I try to get a fresh sample but with your weather it probably is hard for you to get a good one. I usually check when the weather warms in the spring and late summer to make sure they are good. Sometimes I see nothing at all but all new birds are checked about once a week for the first month, just to make sure we have a base.
I enjoyed parasitology when I worked in clinic. I took refresher courses every year for my credits because it was more fun than some other areas. Dentistry was too boring but parasites, that always kept my attention. LOL
I am having fun playing in the poo. I found a hen that looked a little off, so even being cold all I had to do was pick her up and she gave me a nice sample right in my hand, no problem. I ran the exam, twice, and only found one round worm egg so I took the sample to the vet to get a second opinion. There, we found again one round worm egg and cocci. My problem is that I did not buy high enough magnification in my scope. My vet uses 80X and will bump it up to 100X for a closer look. Mine only goes up to 60X.
I have got to tell you how awesome my vet is. On my last visit to have a second opinion done I took my scope with me. She mixed up the sample and spun it, took it out and put the cover slip on it and said, "When it is done check it out on my scope and call me in to see what you find". I was there for most of an hour and she would stop what she was doing every few minutes and check up on our progress.
In the end I could find the cocci on her scope and move it to mine and just barely be able to see it. So if anyone is considering buying a scope make sure you buy one with enough power to see cocci by getting at least 80X, 100X is even better.
It is a fairly short list. There are ways of doing them without a centrifuge, but I wanted to do it just like my vet does so I have one. Also, there are recipes for making your own fecal solution, but again, I bought the same solution she uses off the shelf. Then you will need a microscope with a magnification of at least 80 X. And a book Veterinary Parasitology, reference Manual, or print off the pages you want on line. Small items are the glass slides, glass cover slips, a squirt bottle, a test tube rack, and popsicle sticks.
I am old timey. I do not centrifuge. That was not considered when I was a vet tech or in my yearly continuing education training. I float all my samples. My microscope is old, too but it does reach 100x. I check all the farm animals here and deworm accordingly. I also do ear swabs on the and have on occasion drawn some blood for checks, too but that only lets me know minor things.
Vet taught me to draw blood when I do my NPIP testing. It sure is less stressful to the bird than picking at it with a dull needle trying to make it bleed. I like the fact that you test before and medicate those that need it.