Given a reference list citation of a source with $3+$ authors, which is the correct intext citation to use the first time?

$($Nkosi$,$ Balm, Verona & Stafford, $2017)$

$($Nkosi et al$.,2017)$

$($Nkosi$,$ Balm, Verona, & Stafford $2017)$

$($Nkosi$,$ Balm, Verona, and Stafford, $2017)$