Sippy cup at 6months

Heather
My LO is 6 months and he sits almost on his own. He loves to hold his own bottle. I know you can start introducing a silly cup at 6m. My question is weather I should just replace my bottles with soppy cups? The ones I have have soft rubber tips and he loves them! I feel like I could just replace his formula with the silly cup but can't find anything on it on google. I only read about people giving it to them with water and things about weaning. I just feel like he won't need to "wean" if I were to just switch now but is it too early? I was thinking of silly cups for formula and using the cups with straws or open cups at mealtime with water. Opinions greatly appreciated!!