I certainly think it's worth looking into ABA now, and you can definitely start a suitably tailored programme from around a year old. The youngest I've heard of personally is 15 months (actually the child turned out not to have asd but I wonder if starting ABA so early changed his developmental path?
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In the meantime there are things you can do to help encourage communication and interaction - as someone said, simple things like using whatever he finds most fun (like playing with your hair). So, eg
when he is interacting with you, making eye contact, reaching for something, or doing what you want him to be doing in terms of normal development, make your reaction over-the-top fun, and give him an instant reward of whatever he likes most (eg food/playing with hair/tickle). The message is that by responding so positively, you are reinforcing the behaviour you want to encourage.
Also, talk talk talk all the time, but in very very simple language. Show him everything you are doing, and use one or two word labels. eg when making food, give him the carrot, put his hand on it and say "carrot" clearly. Try not to use superfluous words.
I'd start with the playing thing first though. The key thing is to try and teach him that he gets more from doing something with you than from entering into his own little world.
But please try and enjoy him too - all of us here know that dreadful niggling feeling that something's not right, it prevents you being truly happy about your baby, but also in terrible denial. It sucks, but all you can do now is do whatever you can to prevent/minimise any difficulties - and remember that there is no certainty at all that he will have asd anyway!