Remember when Vegeta came to the Earth for the first time. At that time the dragon balls were used to bring Goku back to life. During the battle Piccolo died and later Bulma and the rest go the planet Namek to use their dragon balls. Later when Piccolo was revived using Namekian dragon balls and they became useless due to the death of Guru, the dragon balls of Earth were used to revive the Namekians.
So, how much time in the Earth days (or months) passed between the revival of Goku and the revival of Namekians?