Here’s a good article from last year that summarizes: https://www.usnews.com/education/best-graduate-schools/top-business-schools/articles/how-much-work-experience-do-i-need-for-mba-programs
My D is planning on 4- 5 years of full time work experience between undergrad and her MBA. She’s not counting her time in undergrad internships and co-ops.
The other benefit of waiting is that her company is going to foot the bill for her MBA.