Turnbull watched his Moneyfields side avoid a potential banana skin against a Totton & Eling side third bottom of Wessex 1 at the weekend.
Two first half penalties from Steve Hutchings helped ease Moneys to a 4-0 win - and a home tie in the second qualifying round against AFC Portchester.
That means a quick cup return to Dover Road for Royals boss Dave Carter and the many ex-Moneys men that followed him to Portchester.
Turnbull, who led US Portsmouth to the Vase semi-final last season, believes Carter’s current club will start favourites on September 25.
He is also hoping to see a large crowd at the tie on a day when Pompey are away at Charlton Athletic.
‘Portchester will be favourites and rightly so,’ Turnbull declared.
‘We might have the Moneyfields badge on our shirts but mainly we’ve got players who were in Wessex 1 (at USP) last season.
‘Portchester are basically a Southern League squad who are playing in the Wessex Premier.
‘They shouldn’t just be favourites to beat us, they should be one of the favourites to win the tournament.
‘It will be nice to get back to being the underdog again. I said to the players at the weekend ‘if there’s any group that know how to play these games without pressure it’s you lot.
‘It should do wonders for our coffers - we should easily get 300 or 400, which would stretch us as the ground’s in the middle of a building site at the moment.
‘But we could fit more in - you could go one or two deep at the train track end, and the stand holds 250.
‘As we know, it’s not a competition with fantastic prize money so it (the gate receipts from playing Portchester) will really help us.’
Ex-Portchester player Bradey Norton was handed his first Moneys start against Totton & Eling up front with Hutchings.
James Franklyn, who had been up top in the disappointing 3-0 midweek loss at Horndean, returned to midfield where Callum Glen and Rob Evans lined up alongside each other.
Midfielders Matt McGlinchey - who had taken part in the Three Peaks Challenge the day before - Jordan Pile and Danny Burroughs were all unavailable while Tyler Moret, who had been due to start up front, was ruled out on the physio’s advice.
Teenager Chad Cornwell was at right-back in a tie which saw Norton and sub Josh Bailey follow up Hutchings’ spot-kick double.
‘It was 3-0 at half-time and a comfortable cruise in the end,’ said Turnbull, whose starting XI contained six of the USP squad that were a penalty shoot-out away from contesting last season’s Vase final at Wembley.
New signing Adam Cripps was also handed his debut.
Moneyfields next travel to divisional rivals Blackfield & Langley in the Wessex League Cup on Tuesday.