Hard start after a few days?

Have you had the battery checked? Perhaps it's getting old and not holding a charge. If the battery isn't the issue, I would think the carb might be.

Since you mentioned a carb, I'm assuming you have the Volusia. The Volusia is notoriously cold blooded at startup thanks to its ridiculously lean factory tune. It is not uncommon for the bike to crank for long durations before firing. The fuel delivery is vacuum operated and any pin hole leaks will cause it to "lose prime" over a few days sitting. I would start by replacing all the rubber under the tank and making sure your choke lever (really just a fuel enrichment rather than an actual choke) is operating.