Borderlands 3 should have at least 1 open beta weekend before the full game release on Sept. 13, 2019. If there are no major problems during an open beta, this would help instill confidence among potential purchasers to pre-purchase. Otherwise, people like me will wait to buy several weeks after the official release until connection/server problems are ironed out.
Also, regarding the Apr. 2020 availability on Steam: I’d like to see a separate open beta on Steam too.