The former Northampton manager was recently appointed as Robins boss with a brief to stop Cheltenham slipping out of League Two and that prospect received a boost in midweek with a home win against Cambridge United.
Johnson adopted an attacking 4-4-2 line-up for that game and is likely to go for the same again at Sixfields.
"It's been a while in coming, but hopefully it's a case of better late than never," he said in midweek. "Back to back performances now become really important.
"We have to keep the momentum and the intent from Tuesday night. Everyone did their job. The wide players, the forwards, the midfielders and defenders all did that against Cambridge."