Bard/warlock multiclass

[Celebris]

So guys...I was thinking about a Bard college of whisper/bladelock multiclass goin lock1/bard2/lock2/bard+ to geth thirsting blade at 5th level...
Is it worth it? I'm not trying to optimize the bard, i'm trying to optmize this particular multiclass.
Since the campaing will start at level five is it better go bard 4/lock3/bard+ to get the ASI as soon as possible?

Stat are str 9; dex 16; cos 14; int 12; wis 10; car 16 going human (no variant).

[TenaciousJ]

A 2nd attack is not that big a deal when you're at level 5 with cantrips that can make up the difference.  Grab Booming Blade and/or Green-Flame Blade on the warlock side and use that for your weapon attacks.

It would help to know how far you intend to go in either class.

[Celebris]

the final build would be like bard 17/bladelock3
I was speculating in adding 3 rogue level to get the auto crit on first round but eventually decided against it.

[TenaciousJ]

You have no reason to go pact of the blade if you're only going to level 3.  You can't take Thirsting Blade until level 5 of warlock.  The only benefit you'll get with 3 levels of warlock is a magic weapon on-demand, and it would seem based on your build that the optimal weapon would be a rapier, a weapon that a bard is already proficient in.

I would suggest either of the other pacts since they do a lot more for you than pact of the blade without its exclusive invocations.  Pact of the tome would allow you to use Shillelagh with a quarterstaff for your build.  Shillelagh learned via pact of the tome functions based on Charisma, reducing the number of attributes you depend on.  Combined with Booming Blade and/or Green-Flame Blade, you'll have comparable melee attacks to attacking twice with Thirsting Blade, eventually surpassing that at level 11.

The assassin level 3 ability is harder to use than you think.  It's only an automatic critical hit if the target is surprised.  Just going first isn't enough to get the auto-critical.