I would say that both patience and persistence are the two most important virtues when it comes to cel collecting. Both are required to snag that most important cel.
As for waiting for a cel, it was about 9 months for a AMG cel on YHJ. I purchased the cel through a deputy but the seller would not come through. It took quite a bit of cajoling by the service and finally the threat of filing a complaint with the Japanese police to get the seller to finally cough up the cel.