When to say I love you

My boyfriend and I have been dating for 3 months. He’s already said I love you to me but at that time I didn’t say it back because I didn’t feel the same way. I’m just wondering when is the right time to say it. I’ve been thinking about it recently and I think I do love him. Before I didn’t want to just say it and not mean it but I think now if I say it I will mean it. For some reason I’m scared to say it. He’s the only one out of the people I’ve dated that I want to say I love you to. I need some advice and input.