When the buy maternity?

KC • Mama to an 18mon old little lady and baby boy is due May 9, '18❤️
I am losing the war on bloating and all of my pants are a damn size 2! I'm not ashamed to start wearing maternity pants but would hate to buy them and have a miscarriage or something. Baby measures 7w 2d but I may closer to 8w based on conception. When did everyone start wearing maternity clothes?