Is it ok to let my 18 month old watch 2-3 minute cartoons a few times a week? Or is no digital viewing advised till they're 2?

i gave my 2 kids ipads for educational apps. my first is 7 yo now , 2nd is coming to 2. i find myself using ipad and watching TV too . in the past my mum allows me to do all this . so i didnt bother to retrict them .