Disengaging makes the the Swashbuckler's Fancy Footwork redundant.
If you're trying to optimize a rogue, build for range. A ranged build can use Hide more effectively to set up advantage, and thus Sneak Attack, every single turn while remaining at relative safety. The Swashbuckler on the surface appears attractive because it's easier to get melee Sneak Attacks, but it does nothing for the fact that melee Sneak Attacks are strategically sub-optimal.
The Swashbuckler has Fancy Footwork because it's made for two-weapon fighting. You can't two-weapon fight with Booming Blade. If you are two-weapon fighting, it's still not likely to get you to safety unless enemies are very slow because you lost your bonus action that would have been used to Dash. It's a very niche ability for a rogue because a rogue just does not get enough attacks to get a lot of use from it. That's why I rate Mobile so much better for monks than for rogues. They attack more innately, and if they have to flurry, they still move really fast.
If you must have rogue levels, I can expand on them a bit in another post.
If you're trying to optimize Booming Blade, sorcerer 3 is going to be a lynchpin of the build IMO. With Twinned Spell and Quickened Spell, a sorcerer could Booming Blade up to 3 times in a single turn if he has 2 targets within range to do so. Find room for Mobile in the build, and you'll have your Swashbuckler effect.
Rogue is hard to fit into that kind of build because it won't be very usable without lots of spell slots and/or lots of sorcery points. Paladin actually does the job better than rogue IMO, because paladin grants more spell slots than any rogue could, and paladin grants Divine Smite at level 2, which scales with spell slots rather than class levels. Paladin 2 and 6 are solid cut off points that would allow you to take sorcerer levels the rest of the way to fuel the tricks.
Paladin 2+/sorcerer 3+ with Mobile would achieve what you want more reliably IMO, and the big bursts work multiple times per turn at the cost of resources.