There is a common misconception that long term relationships can only be created if the beginning is slow. I say, "Who cares?"
What is slow? It would be very pretentious and hypocritical of me to even define this for someone. Plenty of relationships have spawned from one night stands, and countless daters have "waited" days, weeks, months with absolutely no result.
Slow paced, fast paced, red light, green light... it's all relative and dynamic to the two individuals engaging in the relationship. You're going to have to decide which pace is comfortable to you with that specific person.
Long term relationships can't be predicted. With the right amount of chemistry, they just sort of happen. Fast, slow... when you find a person who can stand your neurosis for extended periods of time and you like them back... well, maybe you've gotten yourself into a long term relationship thing.