Perhaps the key moment came in January when Curtis left Ibrox to join struggling Kilmarnock on loan.
After some bright performances at the start of the season for his parent club, both in Europe and domestically, he struggled for game-time – in the six league matches before he moved to Ayrshire, Curtis played just 13 minutes.
However, under Neil McCann and Billy Dodds – who had coached him at Rangers the season prior – Curtis was handed a pivotal role.
He scored five goals in 14 appearances for the Rugby Park outfit, including four in his final five outings as Kilmarnock escaped relegation.
“The staff, players and I are absolutely delighted with this hugely positive news,” McCann said. “We all have an immense sense of pride in Fin earning his spot in Steve’s squad off the back of his time with us.
“He deserves this recognition for the levels he’s shown while on loan here. It’s also a feather in the cap of the football club, and highlights what we can do for players at Killie, no matter the stage of their development.
“Fin has been a breath of fresh air to work with, and we wish him nothing but the best with Scotland this summer.”
When Curtis signed, McCann’s side were 11th on 14 points, just three points above Livingston. They finished on 40 points in 10th, six clear of St Mirren in the relegation play-off spot and 19 above Livi.