Retirement planning for 28y/o

I'm a 28m located in Midwest/Central plains that's married with kids that's trying to plan for retirement. My knowledge of stocks and trading and investing is not good. I contribute 15% with 5% employer match. I'll make between 100k-130k this year depending on how much overtime I work. My 401k is roth and has 63k in it. I figured I would keep doing this for a few years until my 401k hits ~250k, which according to a 401k calculator would be anywhere from 5-8 years. But where do I go from there? I know at that point I should start diversifying. I have 30k student loan debt but it's interest free (my brother is very wealthy and I was fortunate enough that he offered to pay off my debt interest free and I just pay him back $500 a month until it's paid off). My only other debt is my mortgage which I contribute an additional payment to a few times a year.

My brother got wealthy by day trading but I'm not interested in that path. When I ask him about long term investing options he tells me has a financial advisor take care of that. A couple years ago I met with his financial advisor and he basically just told me to keep doing what I'm doing until I have ~250k in my 401k and then I should meet with him again. I want to have a plan with my money though and would like to start thinking ahead so when the time comes I know what to do. Hopefully this post doesn't come across as tacky in any way, I just want to have a solid foundation to be able to provide my family with generational wealth. I appreciate in advance any insight, suggestions, and resources presented to me. Thanks!