Looking at your signature, it looks like he's still a bit shy of a year. I wouldn't worry about it yet. Keep offering it maybe once a month to see if he has any interest, but follow his lead. We started to try at around maybe 10 months. My daughter absolutely and completely refused (like screamed and turned bright red). She had used a straw for smoothies that I made her for a couple months, so it was a normal thing. But at that age, milk is still time for cuddles and the suckling that goes on is comforting and soothing. If he's not having it, wait and try again next month and then again the next. He'll eventually come around to it. At about 13 months, I gave her a straw cup with milk in it for her morning milk. She was busy climbing around on our bed and playing and drank the whole thing straight away and thought it was hilarious. This was a kid who had screamed and turned bright red at even the sight of the straw cup a month earlier! It's just that the timing was right and she was ready. We switched totally to straw cups for the daytime from that day, and switched her bedtime bottle to a straw cup at 15 months, and it was easy peasy. I'd just give it some time until he's happy to try it.
