My idea of the timescales of ESB hinges on the assumption that Bespin is a planet in the Hoth system:
Well, while attached to the Star Destroyer Han says that they’re in the “Anoat system” so they clearly left the Hoth system when escaping into the asteroid field.
According to the EU (both versions) Bespin is in the Bespin System which is in the Anoat Sector.
Either way, Bespin is at least not in the Hoth system.
That would regardless have made Han’s “it’s pretty far, but I think we could make it” statement pretty pointless if it was simply in the same solar system.