The general rule is to express the anal gland when you are giving the dog a bath. Either in the tub or outside. Some dogs glands hardly develop anything and others develop alot. When you feel back there if it feels a little swollen and lumpy it usually is filling up and needs expressing. I do not find it a difficult thing to do, just stinky and messy. I had to learn this the hard way when I had a toy poodle that developed an impacted anal gland. They had to do a little surgery on it to release the impaction and then the vet taught me what to do and when. Easier to keep it expressed than to have surgery.