Couple hours of play time tops. Even quicker if you pop an XP boost and jump into Midtown.
without other leveled characters, it might take longer--especially if you want to go through the story a bit.
Hell, I know I ignore the best advice of veterans for things like this, when playing a new game: I don't care if skipping the story and leveling in other ways is more efficient, I just want to do the story one time through and ease into everything, etc.
To Lupi:
But, leveling gets much faster, the more characters you have maxed, or at least at 50+. I think bonus starts at account-wide 50% XP boost with 1 level 60 toon, 65% with 2 60 toons, and 75% with 3, and so on You get 3% with each level 50 or something like that. The max permanent account boost is 200% on XP. You can see these details in any character stat sheet (I menu), under the extra or "special" stat category, whatever it is.
Just hover over each type of stat to get a nice popup detailing each stat.
OH, also: server-wide 50% XP until Sunday going on right now. And, one thing I learned early is to keep an eye on social chat window. Sometimes, someone will offer up a "Boon Party." Boons (not "boosts"--I still haven't seen a boon and dont' know where to get them) will effect anyone near the user that pops them. So, basically, people meetup at a common place--typically SHIELD Rooftop in Chapter 1, Normal difficulty (so everyone can use it), and just pop whatever boons they have. These stack in duration. They are 25% buff each (XP, RIF, SIF), and depending on how many pop, the duration just adds on--also, timers on boons or boosts do not countdown inside Hubs, so consider them paused when dealing with your inventory.
You don't need to be in a party to get the boons, but you may need to party up to make sure you join the proper instance where everyone is gathered on that map. Then you leave the party so more can taxi in.
Currently, I have 3 days of 25% SIF. some folks seems to wader around with 40+ days going on...