Depends on what kind of shrooms you get. If they are field picked ones, then you will *most likely* need to eat a good amount(5-7 grams). If they are grown hydroponically, then 2-3 grams should be enough for each person.

Not sure if its possible to overdose on psilocybin, but im pretty sure you can make yourself go nearly insane for a LONG time if you eat too much.

If I were you, I would eat the whole dose at the same time as it will hit you harder and faster. I smoked the first time I did shrooms and it was great. I smoked on the come-up and never felt a bit of nausea, and then smoked a little while later after the peak. You will know if you can mentally handle smoking some green once you take them and start to trip.