His dad had to begin Canadian citizenship application at some point. So he could have renounced Cuban citizenship prior to Ted’s birth. I’ve never seen the dates.
Ted's citizenships are first assigned at birth, and that is the moment the constitution examines. There are various legal mechanisms to alter his citizenships as he ages.
Interestingly, that dad was pursuing and obtained Canadian citizenship strengthens Canada's claim on Ted at birth and as he ages. Residence and domicile (the place you call home and always return to) are fundamental to citizenship inquiry.
Ted’s parents needed to have been in Canada for 5 years, and, at the time of Ted’s birth, they had only been living there for 4.
Therefore, although Ted’s dad may have started the Cuban renunciation before Ted was born, he couldn’t have become a Canadian citizen until after Ted was born.