Hi Sheva
Thank you for your question.
You are correct that the failure to immerse a new kitchen utensil does not affect the kosher status of the food prepared therein. And yes, the mitzvah/requirement to immerse it is still applicable, whenever you become aware of the need to do so.
WRT a porcelain utensil, many are indeed accustomed to immersing it without a berachah. (The blessing is recited on metal and glass utensils only.) Others follow the view of Rav Moshe Feinstein, Rav Yaakov Kaminetzky et al. that porcelain utensils do not require tevillah at all. This is my personal practice.
Best wishes
Rabbi Rashi Simon