Eye Contact/greeting someone you know

Hi, this may seem to be a trivial question, but as someone who was diagnosed with high functioning ASD later on in life (18), it's a constant up hill battle to try and improve my self and social game. Since my diagnosis, I've read and absorbed enough information on social psychology that I can come across as a completely normal/neurotypical person, even though on the inside I am just acting and everything is calculated/premeditated.

On to my question: when noticing someone you know walking towards you as you are also closing the distance between them, about how far away do you begin to look them in their eye and begin a normal greeting procedure (slowly opening to a smile, nod up and say "hello"). I have no problem maintaining eye contact during a conversation anymore since practicing over the years and realizing it's importance in social situations. I guess the issue is when I notice someone ahead of me walking in the opposite direction, I just look forward until the person is like, 5 feet away, then I look at them and say hi, and it just seems very forced and awkward.

Again, I know this may seem trivial to most of you, but as an ASD person who is trying to figure out the social aspects of their life, this minor change will probably yield a good return on social capital.

Thanks for your help