The Vanarama Conference outfit beat West Bromwich Albion via a penalty shoot-out to clinch their place in the regional showpiece occasion earlier this month.
Albion, who included five senior pros in their line-up, led for the majority of the semi-final courtesy of a first-half strike from Adil Nabi. But the non-league hosts hit back with 14 minutes remaining through Robert Ogleby.
And with no further goals in extra-time, spot-kicks decided the contest, the part-timers holding their nerve from 12 yards by converting four penalties compared to the Baggies' two.
It proved to be a bitter-sweet evening for Daish's charges, however, as league results elsewhere that night confirmed the club's relegation from England's fifth tier.
Daish, who was Blues' skipper during the double-winning 1994/95 season, took over at Liberty Way back in September with the club third from bottom of the Conference table.
But with one of the smallest budgets in the division, it was always going to be a tough assignment to keep them in non-league's top flight.
And it has subsequently been announced that Daish is to step down from his role after the Senior Cup final.
Boro, a nickname that has stuck with them since the days when they known as Nuneaton Borough before suffering liquidation in 2008, head to St. Andrew's this Thursday (kick-off 7.30pm) to compete for silverware with Blues.
Blues have already beaten a quartet of non-league opponents to reach the final, knocking out Romulus, AFC Wulfrunians and Leamington before needing penalties to see off Coleshill Town in the last four.
Richard Beale's U21s side will face their stiffest challenge yet though as they look to become the first Birmingham City team since 2008 to lift the Senior Cup trophy.
As well as beating a relatively strong West Brom side, Nuneaton caused a cup upset against Wolverhampton Wanderers in a journey that also included wins over Tividale and Causeway United.
Blues last reached the final seven years ago when they beat Burton Albion 5-0 at St. Andrew’s, with Garry O'Connor hitting a hat-trick past former St. Andrew's keeper Kevin Poole – now the club's goalkeeping coach.
Admission prices for the April 30 final are £10 for adults and £5 for concessions. Blues supporters will be located in the Kop, whilst Nuneaton fans will be in the Gil Merrick Lower Stand.