I tag mine at 24 hours - just with the non eid tag as its the lightest. still makes the ear flop for several weeks though - some ears are better than others.
One guy i know uses numbered metal poultry wing tags, they are about 1-2cm long. means they will have an extra tag in their ear though, unless you remove them once you tag them properly.
Previously I have tagged a few weeks later, but it is a lot more effort matching up the lambs to the mothers ... a matter of grabbing one and seeing which mum it runs too! Fun, but time consuming
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