I work in a nonprofit closely related to the field that I will be studying in grad school (full-time MPP), so it just made sense to notify and have my direct supervisor and our executive director write letters of recommendation. They have been very supportive. That said, I think it definitely had an impact on my end of year raise(or lack there of), since they have known since September 2015. Also, they have already opened my replacement position - it stipulates that they are looking for a June hire - ideally they want someone straight out of undergrad so posting now makes sense - but it still is pretty fucked up, in my opinion, especially considering that I am planning to stay in my position through July to maximize paychecks before I'm a broke graduate student. Thank goodness I've already gotten into some programs.