I don't have peacocks but I do have a lot of experience with legbands.
I've used several kinds. My favorites were the colored numbered bandettes. The reason I used those was to have a color for each year and numbers to identify individuals hatched that year. I used the same color code as used for identifying honey bee queens and from afar, I was able to know the age of a bird.
I've used the plastic rings but avoided the metal ones because it would be harder to remove them. The advantage of metal is that they don't come off, which is the disadvantage of the bandettes. I don't know how they do it but they tend to lose them frequently. I resorted to having two on each bird, one on each leg. Sometimes I would still end up with no identification on a bird. By process of elimination, you could tell what bird it was and replace them.
In the end, I finally went with metal wing bands. The bird needs to be handled to identify it but the advantage is they can go on at a few days of age and they stay on for life.
To answer your primary question, I found it better to use zip ties till they matured enough to use (semi)permanent leg bands.
With zip ties, there are all sorts of combinations you can use to identify individuals by use of left, right or both legs, multiple ties and colored zip ties. They are cheap and you can keep changing them as necessary. The main issue with them is that they are not forgiving at all so it is necessary to do your due diligence to make sure they don't get tight.
Bandettes get too tight too but just not as badly as zip ties.