I do not have a veiled, have a panther and werneri chameleons, but I think I can help.
You should be able to sex at any age.
*Male veileds are easy to identify from birth by the presence of a small triangular, fleshy appendage that stems from the crux of the rear feet.
This appendage is called a tarsal spur, and is a reliable method of sexing veiled chameleons.
This was borrowed from a very good site you may want to read in your spare time. Link below
Wish you all the best with your youngster, post some pics for us real soon 
Veiled Chameleons
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