After initially losing 34-17 to France in their first qualification game, Wales followed up their win over Italy with a 39-27 victory over Japanese High Schools. They complete their preparation for the France-based tournament with an international match against Scotland Under 18 at St Helens this Sunday.
Despite some disappointment at their first performance against France, Rees is now satisfied with the side's progression.
"We've had a good amount of time with the group which we narrowed down from an initial squad of over 50 to 32," he said.
"Last month was valuable for us with the capped games against France and Italy giving us a good gauge on the team's development collectively and individually. The friendly against Japan High Schools was also very beneficial because it gave us the chance to give game time to certain players so that everyone could stake a claim for a place in the FIRA-AER squad. Some players put their hands up in that game and have pushed their way into the 26 man group.
"We were disappointed with the performance against France, but improved against Italy, i attack and defence. We'd like to continue in that vein against Scotland this weekend, making further improvements ahead of the England game a week later. We would certainly hope for a much more polished and impressive home performance this weekend than a month ago when we played France.
"In terms of the team selection against Scotland, some players have been given extra game time, while we have kept the spine of the side that beat Italy as they played a smarter game than we showed against France. Others took their opportunities against Japan and have gained a spot."
Looking ahead further, Rees is looking forward to the FIRA-AER tournament. "Our emphasis this week is on preparing for Scotland, and continuing to lift our level of play and intensity but the FIRA tournament will be a great experience for the players in learning about the expectations of international rugby both on and off the pitch, and understanding how they cope with those pressures.
"We haven't set any targets in terms of results, but we want to see improvements in performance along with how we prepare and review games, learning all the time."
The starting XV against Scotland contains eight members of the victorious Blues Under 18 squad that lifted the WRU Regional title in January.
Wales team v Scotland (Sunday 10 April, 2.30pm, St Helens):
Cory Allen (Blues); Owen Jenkins (Blues), Ryan E Evans (Blues), Thomas Pascoe (Blues), Jack Randall (Scarlets); Sam Davies (Ospreys), Rhodri Williams (Scarlets); Thomas Davies (Blues), Jack Dando (Blues), Bradley Thyer (Blues), Jack Jones (Ospreys), Rhodri Hughes (Ospreys), Ellis Jenkins (capt, Blues), Daniel Thomas (Scarlets), Ieuan Jones (Dragons).
Replacements: Evan Yardley (Ospreys), Calum Lewis (Blues), Daniel Suter (Ospreys), Sion Bennett (Scarlets), Lewis Young (Blues), Alex Schwarz (RGC), Rhys Patchell (Blues), Jordan Williams (Scarlets)
Wales Under 18 squad for FIRA-AER tournament - Elite Group:
Backs: Rhodri Williams (Scarlets/ Llandovery / Amman Valley Comp), Alex Schwarz (RGC / Mold / Mold Alun Comp), Josh Davies (Dragons / Llandovery Coll), Sam Davies (Ospreys / Gorseinon / Gowerton Comp), Rhys Patchell (Blues/ CHSOB / Glantaf), Thomas Pascoe (Blues / Mountain Ash / Coleg Morgannwg), Ryan E Evans (Blues / Tonyrefail / Tonyrefail Comp), Jordan Williams (Scarlets / Llanelli / Coleg Sir Gar), Ryan J Evans (Ospreys / Bryncoch / Ystalyfera), Jake Randall (Scarlets / Ammanford / Amman Valley), Owen Jenkins (Blues / Ynysybwl / Pontypridd High), Cory Allen (Blues / Glam Wands / Y Fro)
Forwards: Thomas Davies (Blues / Ystrad Rhondda/ Ferndale Community School), Daniel Suter (Ospreys / Tonmawr / Neath Port Talbot Coll), Bradley Thyer (Blues / Ystrad Rhondda / Ferndale), Evan Yardley (Ospreys / Bridgend Athletic / Brynteg), Elliot Dee (Dragons / Penallta / Newbridge Comp), Jack Dando (Blues / Penygraig / Coleg Morgannwg), Rhodri Hughes (Ospreys / Hendy / Gwyr), Jack Jones (Ospreys / Llandovery Coll), Daniel Thomas (Scarlets / Kidwelly RFC), Ellis Jenkins (Blues / Llantwit Fardre / Bryncelynog), Ieuan Jones (Dragons / Bargoed Youth), Lewis Young (Blues/ Coleg Morgannwg), Sion Bennett (Scarlets /Narberth / Preseli), Calum Lewis (Blues /Aberdare / Coleg Morgannwg )