When is the best time to send my team the 'goodbye' email? I've been with the company for 6 months and have built a good professional relationship with a few colleagues on the team.
Should it be 1 week prior to the last day? The last day?
Usually you do the whole "Goodbye" spiel on your last day. This also includes any email(s) you send.
Doing it before may be awkward, but not exceptionally bad or anything.
Keep in mind that sending goodbye emails has fallen out of usage greatly (at least where I live) and may not even be necessary. Your mileage may vary.
When I leave, I send a goodbye email on the afternoon of my last day.
Since I've already gone around and said goodbye in person to the folks I care most about, I just use the email to publicly say thanks and to make sure everyone has my personal contact information.
It also serves to say goodbye to the remote folks I work with, but can't talk to face-to-face.
You should send your Good Bye Email on your last day, about 15 minutes before you leave.
It is done to avoid fuss and avoid distracting others. If done at the end of the your day , people do not have the time to react. In the mail , you have specified your contact. So if needed they will contact you. It is just professional to avoid any melodrama/distractions/confrontations. Have seen this done in top 10 financial companies usually