Bladesinger. Is a fighter dip good or bad

[Whit]

Since bladesinger is a wizard but goal is to augment fighting , I was thinking fighter dip at lvl 1, 7 possibly again at X lvl ? to get samurai

1. Get con saves
2. Get action surge cast two spells from distance or double melee to (4)
X . Advantage on melee attacks maybe get elven accuracy with it.

Cast spells if needed over melee but then enter melee with

Upgrade shadowblade and mirror image

Toss in maybe sentinel

Fighter 3/bladesinger 17.

Is the dips pro or con fir a bladsinger.

[Trickery]

Two levels of fighter for action surge and a fighting style is fine. You probably don't want more than that. Wizards have enough ways to gain advantage (and enough reasons to not need to enter melee combat) that you probably don't need Samurai. Starting as a fighter will get you Con save proficiency which is generally seen as a big plus for Bladesingers.

[Dork_Forge]

Since bladesinger is a wizard but goal is to augment fighting , I was thinking fighter dip at lvl 1, 7 possibly again at X lvl ? to get samurai

1. Get con saves
2. Get action surge cast two spells from distance or double melee to (4)
X . Advantage on melee attacks maybe get elven accuracy with it.

Cast spells if needed over melee but then enter melee with

Upgrade shadowblade and mirror image

Toss in maybe sentinel

Fighter 3/bladesinger 17.

Is the dips pro or con fir a bladsinger.

A fighter dip is great for a Bladesinger, especially if you start with a Fighter level. If you go 3 deep in the dip (which is certainly beneficial) I'd recommend taking the additional fighter levels after you hit Wizard 3 to get Shadow Blade online.

As for subclasses Samurai is a great one especially since a familiar can't be counted on for advantage on the first round (and temp hp always helps those wizard hit die), Battlemaster is universally great but Eldritch Knight will help with slot progression for upcasting.

[Nagog]

I'd recommend one, maybe two levels of Fighter for it, but beyond that there isn't all that much that's worth sacrificing spell progression for.

[OverLordOcelot]

The big thing to be careful of is that non-caster dips really hurt your spellcasting ability. It's not unworkable, but it does mean that you'll be a level or two behind with getting cool new spells, and if the campaign runs to a high level but not 20 you'll end up never getting to use the highest level spells that you could have as a single class.