I would also recommend applying for an MBA now. The average years of work experience at most programs is 3-5 years upon starting and you would have 2.5, which is slightly on the low end but not significantly. (I don't think working on your business plan would technically count as work experience). The fact that your experience comes from a start up & from your family business also makes it "count" more in some ways, since you typically have higher levels of responsibility in both of those environments than you do in a typical "job." Plus, you are coming from a unique industry which will contribute to class diversity & help you stand out. In other words, the diversity you bring will make them more willing to overlook weaknesses in your application.
In addition to that, it's actually tougher to get into b-school when you already have a MsF. Business schools like to see work experience, like you said, an having a masters in a business-related field not only makes it a lot tougher for why you now need an MBA (since you will have already filled some skill gaps through the MsF) but it also makes them nervous since they don't like to see "career students." In adidtion to that, from an employment standpoint, the MBA is just as strong, if not stronger when it comes to job prospects, in part because it broadens your options & network. So if you ultimately DO really want to MBA, I think you'll have a much stronger application if you apply now vs. if you wait & get the additional degree first.
If you do apply to b-school, my advice would be to strongly consider saying you want to return to either your start up or your family business post-MBA when you talk about career goals. Adcoms love family business candidates as well as candidates who have had SUCCESSFUL start ups. Both are great to have on your resume (because you've usually been able to have more significant responsibility than you could at a typical "job"), and they also love family-business post-MBA goals in particular (because 1) you essentially have a guaranteed job, which is good for their employment stats 2) you can typically go on to have big impact in your career at a family business - again since you have access to higher levels of responsibility more quickly - and they like to have alumni who go on to have significant impact. You can also make a strong argument for why you need an MBA to grow your family business (in terms of the skill gaps you need to fill). A family business post-MBA goal would help set your application apart, help compensate for the slightly lower than average years of experience, and help outweigh a GMAT score that is also a little lower than ideal. Or, if you have someone who can run things at your start up while you are in school that could make sense as a goal as well, especially if you have shown demonstrated success in the start up.
At the end of the day, you want to be genuine in your goals, but at the same time they know none of this is written in stone and that many applicants go on to do something other than what they said they were going to do in their essays. These applications are an art form - you want to be honest but at the same time you want to tell a story that's going to get you in to the best school possible!
In terms of target schools, it would be awesome if you can improve your GMAT, no matter which program you apply to. Even getting your score up to 680 would make a difference & a 700 would be totally awesome. I'm not sure if you have time for that before the upcoming deadlines, but if you wait a year to apply then you won't even be on the low end in terms of years of experience for an MBA. So that would be one option to consider as well. But even if you don't get your score up, I think the strengths that I named here (start up & family biz experience, unique industry, potential family business or start up goals) will help compensate for that score.
Hope that helps! Definitely reach out to us if you'd like more help thinking through all of this! Claudia can set you up with a free consultation. I'd recommend our consultant Julie Bowman in particular. She works with a lot of our family business candidates & can help you formulate a strong story so you can get into the best school possible & could also help you think through that MBA vs. MsF decision. You can reach Claudia at
claudia@admissionado.com