When can you castrate a male cat at the earliest without it being adversely affected in appearance?

We have a Siamese mix and even though he is only four months old, we think he is starting to reach puberty!

It is not that we intend to rush off and castrate him now, but we would like to do so before he starts peeing inside and so on. What do you suggest?

Thankful for any answer!

The Cat Advisor Changed status to publish May 29, 2022