A 6:45pm kick-off allows plenty of time for the nerves among supporters to set in as the Cobblers aim to protect the advantage given to them by Roy O'Donovan's goal in Thursday night's tie at Sixfields.
Town were good value for at least that single goal lead and Cheltenham boss Mark Yates admitted afterwards that he was happy to avoid going home after a heavier defeat.
Both sides face a quick turnaround in their bid to reach Wembley and Aidy Boothroyd will know that his men have struggled away from this season.
He was confident going into the play-offs that those problems had been addressed and will take further heart from the discomfort that O'Donovan, Bayo Akinfenwa and Chris Hackett caused the Robins on Thursday.