The elimination ties have been brought forward slightly to Monday, May 23 and Tuesday, May 24. They had initially been set for Wednesday and Thursday.
The semi-finals remain on Saturday, May 28 and Sunday, May 29.
And the final will be on Sunday, June 5 at West Ham United’s London Stadium.
All ties are single-leg matches with extra time and penalties used if necessary.
All matches will be broadcast live on BT Sport.
The Spireites could also still qualify if they lose but they would need Dagenham and Rebridge, who are three points behind but have a better goal difference, to not win at home to title contenders Wrexham.
A win for the Daggers and a defeat for Town would see Paul Cook’s men miss out.
Confirmed schedule of the Vanarama National League play-offs:
Eliminator A – Monday, May 23 - 5th place vs 6th place – 7.45pm
Eliminator B – Tuesday, May 24 - 4th place vs 7th place – 7.45pm
Semi-final – Saturday, May 28 - 2nd place vs winner of Eliminator A – 12.30pm
Semi-final – Sunday, May 29 - 3rd place vs winner of Eliminator B – 12.30pm
Final – Sunday, June 5 – 3pm