2009–2014 : Schoolboy rugby / SWD

Jackson was born in Calvinia, but grew up in Riversdal in the Western Cape, representing the SWD Eagles at various youth levels. He earned a provincial selection as early as primary school level, when he played as a fly-half at the Under-13 Craven Week held in Kimberley in 2009.^[2] He was the top scorer for SWD at the Under-16 Grant Khomo Week in 2012, scoring a try, seven conversions and three penalties for a total of 28 points in his three starts,^[3] at the Under-18 Academy Week in 2013, when he scored 20 points through four conversions and four penalties,^[4] and at the Under-18 Craven Week in 2014, scoring two tries, six conversions and two penalties for another 28-points haul.^[5]

At the conclusion of the 2014 Craven Week, he was also named in a South Africa Schools team hosted three matches in an Under-18 International Series. Jackson started all three matches; after featuring in a 28–13 victory over France,^[6] he scored one try in each of their matches against Wales^[7] and England.^[8]

2015 : Blue Bulls, Tuks and South Africa Under-20

After school, Jackson relocated to Pretoria, where he was amongst the Blue Bulls Academy intake prior to the 2015 season.^[9] He joined the UP Tuks rugby team – the Pretoria-based university side affiliated to the Blue Bulls Academy – for their 2015 Varsity Cup campaign. After playing off the bench in two matches, Jackson established himself in the starting line-up for the remaining five matches of the season. He scored tries in their matches against CUT Ixias,^[10] UJ^[11] and in their semi-final defeat to NWU Pukke.^[12]

Jackson was named in a 37-man training squad for the South Africa national under-20 rugby union team^[13] and started for them in a friendly match against a Varsity Cup Dream Team in April 2015.^[14] He was then included in the squad that embarked on a two-match tour of Argentina.^[15] He started both of their matches against Argentina helping them to a 25–22 victory in the first match^[16] and a 39–28 victory in the second match four days later.^[17] Upon the team's return to South Africa, he was named in the final squad for the 2015 World Rugby Under 20 Championship.^[18] He started their 33–5 win against hosts Italy^[19] and their 40–8 win against Samoa^[20] in their first two pool matches. However, he dropped out of the squad for their 46–13 win over Australia in the final pool match^[21] and also didn't feature in their 20–28 loss to England in the semi-final^[22] or their third-place play-off match against France, where South Africa achieved a 31–18 win to secure third place in the competition.^[23]

Jackson returned to domestic action in South Africa, appearing in all fourteen of the Blue Bulls U19' matches in the Group A of the 2015 Under-19 Provincial Championship.^[24] While Tinus de Beer was the main goal-kicker for the team, Jackson also contributed 50 points with the boot during the competition, in addition to scoring tries against Golden Lions U19,^[25] Free State U19 (first in an away match^[26] and then in the return leg at home),^[27] Western Province U19^[28] and the Sharks U19^[29] during the regular season, as well as in their semi-final match against Western Province in a 30–29 victory.^[30] Jackson also played in the final, but could not help his side to winning the championship, with Eastern Province U19 winning 25–23 in Johannesburg.^[31]

2016 : Blue Bulls and South Africa Under-20

In March 2016, Jackson was again included in a South Africa Under-20 training squad,^[32] also making the cut for a reduced provisional squad named a week later.^[33]

In between training with the team, he returned to the Blue Bulls to make two appearances for them in the 2016 Currie Cup qualification series; he made his domestic first class debut by starting in a 20–17 victory over a Free State XV^[34] and also started their 17–38 defeat to Gauteng rivals the Golden Lions XV a week later.^[35]

On 10 May 2016, he was included in the final South Africa Under-20 squad for the 2016 World Rugby Under 20 Championship tournament to be held in Manchester, England.^[36] He started their opening match in Pool C of the tournament as South Africa came from behind to beat Japan 59–19,^[37] and played off the bench in their next pool match as South Africa were beaten 13–19 by Argentina.^[38] He was restored to the starting line-up for their final pool match, as South Africa bounced back from their defeat to secure a 40-31 bonus-point victory over France^[39] to secure a semi-final place as the best runner-up in the competition. He started the semi-final, as South Africa faced three-time champions England. The hosts proving too strong for South Africa, knocking them out of the competition with a 39–17 victory.^[40] Jackson also started against Argentina in the third-place play-off match, but suffered their second defeat to Argentina in the tournament, convincingly being beaten 49–19^[41] to finish in fourth place in the competition.

Jackson made one further start for the Blue Bulls in the Currie Cup qualification series after returning to domestic action, starting in a 95–12 win over Namibian invitational side the Welwitschias.^[42]

Jackson was then named in their squad for the 2016 Currie Cup Premier Division.^[43]