I think the welcome notice is not that important. it seems like you got what you need, which is the green card. so there is no need for you to Infopasss to get them to give you a welcome notice which i think wouldnt be possible any ways. if you want to know what is a welcome notice, I found this in another forum:
"Welcome notice is generally sent after the I-485 is approved by Local USCIS after interview they send the file back to service center and service center sends the welcome notice and then the Card is sent in 8-15 days after welcome notice. Welcome notice will have different # and it is NOT I-485 receipt#
** if your I-485 was not approved at Local office then send Form G-731, - Inquiry About Status of I-551 Alien Registration Card"