Honestly, most schools don't put a lot of stock in work experience during college, especially if its something that you dont need your degree to do. You may be a real estate agent but that doesnt require a college degree and they wont care if you own one, two, or three houses...unless you have a large real estate portfolio of rental properties you manage as a company that doesnt mean much.
You are far better off working for 3 years, doing some very unique ECs, being very involved, study hard for the GMAT and aim high. Then apply to top 20 schools which you could easily groom yourself into a solid candidate for. With the knowledge that you want an MBA and what schools look for you have a HUGE advantage with making yourself into an ideal candidate no matter what your undergrad. People get into Harvard from no name schools, its just they have a very good profile besides their undergrad brand name. Study hard get a high GPA and do well on the GMAT and it will go a long way to proving you can cut the academics at any schools program and then have a profile that is well rounded and NOT average. Then apply to better schools than you have a good chance of getting into right out of school. Look on the MBA page of the school you want to go to, see if they have career placement stats, assume you will be on the low end since you have no prior experience. Then look at a top 20 school which you would have a good shot at if you prep yourself for it for the next 5 years. The difference over your lifetime could mean more money and career opportunities than you can imagine.
I am sure that the majority of people on this board are going to tell you to put off your MBA until you are 25-26 and have worked for several years. Without prior work experience an MBA from a Tier 2 school is only going to provide you so much. You will be competing for jobs when companies visit campus against people with more work experience, thus stronger resumes. Look at the top schools and see how many kids right out of school go there, you can count them on one hand and there is a reason for that. Its not law school, MBAs are designed for people with real world post-undergrad experience.