Among the first of the 313 from Basra is Ahmed (scanned page)

And from Basra: Abdulrahman bin AlAtaf son of Sa’ad and—- Ahmed—- and Maleeh and Hamad son of Jaber.
p.232 Besharat AlIslam

This confirms the Prophet’s will that the first believers and first of the close ones is Ahmed a.s (you can review the thread of the will with its scanned pages of Gaibat AlToosi in English.)

Cover page and p.232 below