Hi
Staterooms are usually ready around 1.00pm, so when you board you go and eat and then have time to wander around for a short time.
Make sure you have your swim things in a carry on, as you may not see your bags until late afternoon, 4/5ish!!
If you go to your deck, they have a ribbon type thing across the entrances to the cabin corridors, so you can't get through - they are very busy doing the changeover clean and linen change.
However, when this is lifted, you can go to your cabin, but your bags are unlikely to be there. You then have until 4pm when there is a lifeboat drill, basically it means that everyone (used to take life jackets, but no longer need to I believe), goes to their 'muster station' - the place where you meet to get on your lifeboats. It may be a lounge or restaurant or even on a deck - the location is on the back of your cabin door and written on your life jacket. You get there and you sit or stand around, until they check you are there and then off you go, to await your bags.
The Sailaway party last time was 4.30, although on one of the Meds last year, we had the party, but the ship sailed really later which was a bit weird! The Sailaway finishes half an hour before the first dinner seating, which is at 6.00pm.
3pm is a good time to meet, as there is that bit of time between lunch and then lifeboat. However, I found it very rushed before, as I wanted to go to the Spa to look around and to reserve some tastings for the next day!!!

It would have been nicer to have had time to have a drink with everyone, so I think up on deck after lifeboat, just before Sailaway, which starts at 4.30 may be easier, but nothing to stop people meeting at 3pm and then carrying on later!!!
I was just looking at last years Navigator for Day 2 At Sea and they have:
12.30pm Wine Tasting
2.30pm Teguilla/Margarita Tasting
4.00pm Beer Tasting
10.30pm Cognac Tasting.
Could be a busy afternoon!!!!!!

(roll on floor, but not laughing!)
Kate