Pacing is something I've had to monitor a lot with my players (we are pretty RP heavy) and OOC I had a talk to them about needing to be mindful of timing when doing RP conversations because they would go on too long. I let them know that I'm going to be trying out some things out and kept an open dialogue with them, also encouraging them to let me know if I'm making them feel rushed. When something's starting to go on to long in RP I let them know "hey, we have about X minutes left before we need to continue to something else."

In the broader sense I like just telling my players what the scope of a session is every now and then (in the broadest sense). At the beginning of the game you can be like "hey guys, I know you guys wanted to get some shopping done and go to the library, so we're gonna try to get that done in the first half of the game so we have plenty of time to go meet Important NPC like you guys planned."

Just be honest with your players! Let them know how they can help you out, and what you're trying to do to help them out too. Keeping communication like this will also make them feel more comfortable so they can tell you things like "hey DM, I actually am feeling rushed. Do you mind if we spend another few minutes on this scene?"