I hope not.
That ought not to be a main priority for Meghan & Harry when selecting a wedding date if they do decide to move onto the next stage. The way I see it, as long as the monarch is ok with the plan and unless the date coincides with prior royal engagement dates, I see no reason why they shouldn’t go ahead with a wedding date of their choice.
And in any case if Kate would really like to attend the wedding then like most pregnant women before her, nothing aside from ill health precludes her from doing so right up until the eighth or even 9th month pregnancy. Perhaps a rounded belly on show will be an issue for her but I’d like to believe she isn’t that shallow. Besides, she was far gone in the third trimester of her last pregnancy before stepping aside from public duties to enter into confinement.
Harry has always voiced support and been there for her and her family as she eased her way into the royal family. It’d be nice if kindness is repaid so hopefully she’ll be there for Meghan, too.