Lots of people do this or an overnight mash. If you boil some friday night, it might be better. The fear is that the lacto that is all over the grain will start to sour your wort until you boil it. Also, if you don't boil or mash-out, the extended time at lower temps could really dry the beer out, like mashing at a low temperature. I did this for my first all-grain without knowing the above, and it wasn't a problem, although it finished a little dryer than subsequent brews. I mashed/sparged around 5-6 pm, I think, and did the boil the next morning.
Search for overnight mash and other related threads and you'll find a lot of debate and experience.