Hi,
Not only he's understanding, but he's making sort of connections with real life. And he'll recognize math in things he sees in the real world. For instance, the numbers will be highlighted for his brain when his eyes detect them - even though he's not telling you that. That's not to say you won't need to show him connections between math and using math in everyday life.
When we first started LM with our son he was 2 years and 2 months old. So we've been using it frequently, at least once a day on average for more than a year. I'm not doing much with him, just using and showing math when I have the chance, not too often.
Although since spring we have been using other programs with math stuff, he has learned to name numbers with LM, he loves to repeat them after hearing them. Also, thanks to LM, he's speaking out loud, when he wants to, equations. He does that when he recognizes numbers or even math symbols.
If I were you, I would just go on and use whatever icons and method he likes and just let him show you when and what he knows. He'll do that at the right time for him.
I'm not worried about LM or math anymore. He's learning it, that's sure, if I can make it fun. He's enjoying it - and that's what I want for him.