The dose is 100,000IU.

How will you know the appropriate dose if you intend to give by yourself? It is better to take at the health centre.

It is not late. Kindly take your child to the health facility for them.

If you are following the Nigerian immunization program then what you will be given at 12 months is oral vitamin A, but there are other Non-NPI vaccines like chickenpox and meningococcal vaccines which can be gotten from private hospitals.

Yes, he can still take it. Just that he may be at risk of vitamin A deficiency but if he is eating food rich in vitamin A like meat, liver, carrots e.t.c he will be fine. Most of our flour, sugar, vegetable oils are also fortified with vitamin A so if he is taking that, he will be fine. Kindly note that vitamin A is a supplement, not a vaccine.

Use another health centre.It's expensive in private hospitals