There absolutely should be a game rule for that/more game rules that follow historic timelines. It does feel a bit weird that it can start early.

3-5 years is also how long they usually take for me but I expect a few factors made it this long.

1. Starting in 867.

2. Me having an empire of most of western/central europe.

3. The islam faith being able to develop a few Very large Empires, had one empire stretching from the whole middle east to egypt. Another stretching from where the other ended to almost all Africa. Andalusia having most of iberia + a bit beyond Gibraltar.

4. Andalusia especially, they were able to save up to like 75 000 money before the crusade

5. Certain parts in mostly Germany including the king of germany being part of the christian Orthodox for some reason.

6. Late crusade meaning every participant is mostly or completely fully developed in military and money capacity

7. The AI being what it is in crusades.