Vatican - How to sequence my stops

Doing the Dome before a 10AM entry to the museums would be a mad dash.

If you are doing the 10AM museum entry, do the Dome afterwards

Thanks. I haven't booked the museum tickets yet. What time would you suggest i do the museum, if i do the dome first?

http://www.vaticanstate.va/content/vaticanstate/en/informazioni-utili.html

This above provide some helpful info ( in case you have not already found it)

The Dome opens at 8--- I would give yourself 3 hours to go up, enjoy the view/experience, get back down and get from the Basilica to the Museum entry which is a 15-20 minute walk from where you reach 'ground level' ...... Presumably you are planning to visit the Basilica itself after touring the Museum?

You cannot buy dome tickets in advance, only on site. The climb up the dome takes a while so give yourself plenty of time. You might even consider doing it on a different morning so that you can tour the museums at 10am.

Donna

I think the basilica opens at 7 a.m. If you get there early, you will benefit from the lack of crowds - no waiting for the security check, and lots of quiet time in the church. It took me about 1.5 hours for the dome, using the elevator (saves you some stairs but not all that many). I took my time climbing pretty slowly, several times resting and letting others pass me and more time taking photos that most people (you will have to jockey for position), and stopping for a drink on the balcony and more photos. If you do this on the same day as the museums, it's best to do the dome/basilica first. After the museums, you'll have a long walk back to piazza, then wait in line for security, then wait in line to go up the dome - there's limited capacity, so the lines tend to get backed up, and there will be gobs of people in the church too. Sometimes you can take advantage of the shortcut from the Sistine Chapel to St. Peter's and avoid the long walk and the security check. It's supposed to be strictly for tour groups, but some guards are lenient. The trouble is that you can't count on being able to use it. Mondays are typically the most crowded at the museums, so it's better to choose another day if you can. And avoid Wednesday if there's a papal audience - good morning for the museums, bad for the church/dome.

The Vatican Museums are huge. Plan ahead for what you want to see. And don't be disappointed if some rooms are closed. On both my visits, the Etruscan rooms were closed.

You can pay for an elevator ride to make the Dome (and the lovely views from the exterior roof) less work and less time. But the real issue about the advice you already got here is the DISTANCE, TIME, and LINES from St. Peter's (where the dome is) to the Vatican Museums, which have their entrance nearly half a mile away as walking, if only 1/10 mile as the crow flies.

You will be able to use the special Timed Entry line for the Museums, much shorter than the no-ticket line, but you will have trouble telling them apart, and learning the lay of the land. You are not just going to pass through a doorway at 9:59AM. You may also be slightly overplanning.

Some people (using the Search box top center you will learn there are moral/obedience issues ... ) prefer to exit the Sistine Chapel directly through a one-way exit reserved for tour groups. That is a fast connection, but it is the opposite direction (and it runs the OTHER WAY) from your OP question.