Normally it takes about 24 hours for github to generate certificate for the given domain.
However, you might also want to check for your domains record. As in my case i had created sub domain WWW and pointed to the apex (main) domain. if you are doing something similar then make sure to point it to your *.github.io
Yep, had checked that, thanks.
Time heals all wounds. And apparently GitHub pages cert errors. It's working :)
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