Passover takes place at twilight as the 14th of Abib begins. Unleavened Bread begins 24 hours later on the 15th of Abib. The Passover is a preparation day.
Nine steps had to be included with the Passover observance, all within the house until morning. It takes place between sun's setting and complete darkness.
The wavesheaf offering is reckoned from the weekly Sabbath within the Days of Unleavened Bread. It had specific requirements that were not met in Joshua 5.