Poston, who won his first tour title at last month's Wyndham Championship, fired six birdies and an eagle in his bogey-free start to share the 18-hole lead at the Country Club of Jackson in Mississippi.
Storms halted play Thursday afternoon with dozens of players yet to finish their first rounds.
Play resumed Friday morning, with early finishers going directly into their second rounds in a bid to get the tournament back on schedule by darkness.
Poston, the first player since 1974 to win a PGA event without making a bogey, matched the start of Hoge, who rolled in a 46-foot birdie putt at the 18th hole Thursday to cap his 64 before the storms struck.
South Korean An Byeong-hun and American Scott Stallings were another stroke adrift.