Have personal knowledge of a player who wanted to wait for a "bigger" school to come around. Kept showcasing and kept playing, talking to coaches, etc. When he was finally ready to commit, the school said: " we don't have any money or spots left." The player is now at a JUCO with no scholarship. Take it for what it's worth. I would negotiate now (or within a short time frame) if you feel the offer was too low.