My first one will be almost 2.5yo when the second one comes out 😊. I feel a 2 year gap is ideal as they can grow up together closely. Right now my first doesn't understand much but I keep telling her mummy is pregnant with your adik, you will have an adik soon. Maybe she won't understand now but once the baby comes out I'm sure she will adapt quickly. Most people say having 2 under 2 is a big struggle so I feel 2.5 and newborn isn't so bad (hopefully 😅). Anyway you should try sooner than you think as conceiving might take some time.
I don't think there is any perfect age gap. some prefer close and some prefer wide and all managed well. it is difficult to totally comprehend or be prepared to be able to take care of 2 when u only have 1. every parent learn along the way. trials and error on what works and what doesn't.
https://sg.theasianparent.com/best-age-gap-kids