Noah is nearly 18 weeks old and he still wears them day and night, and I have no intention of putting him in proper outfits on a regular basis anytime soon. If we are going out somewhere for an occasion, then I put him in an outfit, but otherwise it's babygros.
I think he has all his life for clothes, and I also think they are much more comfy than trousers with a wasitband across his back whilst he is lying down a lot. I think when he can sit up more then I will start putting him in clothes in the daytime, so probably not til he has passed 6 months old.
I'd wear a babygro if I could, they look so comfy.