It takes much longer than 48 hours after docusign. Wait about two or three weeks after you docusign, then talk with your local dealer if he hasn't contacted you first.
1) SS needs to file and get approval from the ATF for a Form 3 to transfer the suppressor to your local dealer. That takes about a week usually.
2) SS needs to ship the suppressor to your dealer. That can take a week or more.
3) Your dealer needs to do their part in the SS software to download all your info into a draft eForm4 in his account.
4) You and your dealer need to get together and actually submit the eForm4 to the ATF using his account and your ATF login and PIN. This is the part they are talking about when they say 'Certify'.
5) Now wait for approval in ~90 days-ish.
Getting to step 4 has been taking me about a month at best.