The East Londoners beat off competition from a number of top European clubs - including London rivals Arsenal and Chelsea - to complete the signing of the highly-rated young Portuguese forward last month.
The 16-year-old was signed on a two-year scholarship deal with the Hammers and will pen a professional contract when he turns 17 later this year, according to reports in the likes of the Evening Standard.
Quina actually chose the Hammers after spending a month training with the club before leaving to play in the Under-17 European Championships - which he won with his home nation Portugal earlier further underlining his burgeoning potential.
Mr West Ham Mark Noble
'Mark Noble told me he had heard about me before'
A quick, skillful striker with a penchant for the spectacular, a grateful Quina has taken to social networking site Twitter to reveal some sage advice offered to him by his new captain Mark Noble.
"Big thank you for all the messages from the West Ham fans I'm going do my best all the time for the football club and fans," he said on Twitter.
"Mark Noble told me he had heard about me before and told me to just be myself, feel normal and do my thing and try to do everything right."
Big thank you for all the messages for the @whufc_official fans I'm going do my best all the time for the football club and fans— domingos quina (@domingosquina) July 4, 2016
@Noble16Mark told me he had heard about me before and told me to just be myself, feel normal and do my thing and try to do everything right— domingos quina (@domingosquina) July 4, 2016
West Ham's Martin Samuelsen
Prodigal crop of youngsters
Quina joins the likes of Antonio Martinez, Martin Samuelsen, Reece Oxford and Reece Burke as a crop of youngsters at the club with genuine potential to gatecrash the first team.
Whether that will be this season or not remains to be seen although their level of first team involvement could very much hinge on the club's progress in the Europa League.
West Ham manager Slaven Bilic
Europa League progress could be key
Bilic's side face two, two-legged ties to qualify for the competition proper which would then add a further six games to the fixture list.
With the extra games, Bilic will be keen to blood his talented crop and give them vital competitive experience.
Mauricio Pochettino followed a similar policy at Tottenham Hotspur last season and it helped the club stay fresh for the Premier League as they secured Champions League football.