It's not recommended, but people have done it. I've talked to many people who have done it, and very few of them would ever do it again
Especially since your overload term is first term of first year, when you're going to be getting used to everything and it can be pretty overwhelming. Splitting it 15-15 is the ideal way of doing it, but if you really want to take all of your first-term courses and none of them can wait until the summer or second year, then that's your choice. It's not impossible, but it will definitely require lots of work.