The first date is probably too soon. First time you sleep together is also probably a tad hasty. No one likes throwing it out there if it's not going to come back to them, so the best time to say it is probably when you know the feeling is reciprocated. There's a fine line between lust and love, and the two are easily confused. The only way to know which it is, is with time, experience… and each other.
There is that rare breed of human who has no problem putting his or her love out there with no need for anything in return. But if you're asking this question, you're probably not one of them.
At what point is a penis considered too big?
Umm… the moment it stops feeling good. More commonly, it's men wondering if they're big enough -- not that there's too much to go around. The widespread misconception is that bigger is better; but the truth is, not all vaginas are created equal. And, every woman swears it's really the girth that matters more. Every woman's interior square-inchage is different.