you should expect silence for about 2-3 weeks. IRCC will open it, confirm everything has been signed and the correct forms are included and send the sponsor an "acknowledgement of receipt" (also known as AOR). Then, IRCC moves on to processing the sponsor's application and will send an approval letter (known as SA) another 1-3 weeks after receiving AOR. It's best to check the thread specific to the month you send your application so you can track when others are receiving notifications from IRCC. The timing for SA goes up and down based on application volume and other seasonal factors.
Once that's done, the application will be transferred to the appropriate visa office (Ottawa for US applicants), and it will sit in queue until it's picked up for processing. Generally speaking, US applicants are getting approved in 5-6 months, so there will be more silence until IRCC contacts the applicant about any additional document request, their passport request and visa processing.