I really feel you on this because I had the same question when my girl was about 6 months old and I was looking at Heguru too. From what I heard from a friend who brought her son for a term, the classes are quite gentle and sensory-based, so the babies seem to enjoy the stimulation even if they are too young to understand the content. She felt it was more about creating a rich environment for the child rather than any hardcore drilling, and her boy did seem more alert and responsive over time. That said, I think the biggest benefit she noticed was actually spending that focused, playful time together with her child, which any parent can do at home too. Maybe just try one trial class first and see how your little one responds before committing lah.