I don't think there is a set time for seeds to be dry (mature) prior to planting. I've had 'volunteers' sprouting up from a seeded plant I was going to use as a strain. My own personal preference...I like to have them sit in the dark (like on a jar lid, or small tray) for about a month before sealing up....or using.
Am no botanist, but, as far as I know, a month of drying should do it.
Also, you might want to look into stratification. It involves imbibed seeds and chilling (not freezing) to simulate the natural transition from the winter to spring seasons! But, with just 3 seeds I don't know if you want to risk it.