England's Archer 'fully back' from long injury layoff
Archer, who has not played international cricket since March last year, was ruled out for the season in May due to a stress fracture in his back.
Before that he had been sidelined by an elbow injury which required a second round of surgery in December 2021.
Archer bowled nine overs on Wednesday, the opening day of the match, and was 39 not out at the end of the second day's play.
"Yesterday was a really, really big day," he told reporters on Thursday. "A small day but still a big day.
"I will say I'm fully back."
Archer said his goal was to get back into the test side but would not rush things.
"Obviously to get back to the first team is my number one priority but also getting back there as safely as possible," he added.
"I'd rather take these last few months very seriously, more serious than probably all of the rehab, because once this phase goes right then it can set me up for the next three to four years injury-free.
"I would love to play every game, but I don't think the physio would let me. Our squad is strong enough that I can play all formats all year round."
Archer is not part of the squad that will begin a three-match tour of Pakistan starting next week but he is targeting a spot in the team for next year's Ashes series, which will take place on home soil in June.
"I'm more than prepared to do some extra bowling and stuff in and around some other cricket, just to put my name in the hat (for that series)," Archer said.
Archer is expected to feature for Mumbai Indians' Cape Town franchise in January in South Africa's new Twenty20 league after he was announced as a wild card pick on Wednesday.