If you consider the 767 a wide body, it’s attainable as a new hire at United. There’s no seat lock to bid up in pay, but you will be forever junior as you watch people bid ahead of you. You won’t fly much, since we bid flying FO and bunkie separately.
777 and 787 can be held at about the two-year mark, mostly in SFO but EWR isn’t far behind. A few held it in ORD as we staffed up for the 773s, but it hasn’t been that junior since.
Unless you’re just desperate to fly a big airplane, your QWL will be vastly better on a narrow body until you have some seniority.