If you join as an experienced FO, time to Command could be "relatively" short, but it will be a "Contract Command" ,& only if the company continue to seek those to accept them.
The full-time FO's have to take a "leave of absence" from their permanent positions to do so, and by doing this lose out (I am told) big time on other important things like pension contributions etc etc. Thus, so far, few, if any permanent FO's have made the choice. . whereas, quite a few Contract Capts have applied for the 35 (soon to be 50 if rumours are to be believed) permanent FO positions up for grabs (even with such "exotic" bases as BGO/SVG/TRD)
That gives you some idea of the difference between a "permanent" NAS contract & a "Contract contract"