No expert here, but I'm a fan of limiting carbs when looking to drop some fat. Everyone is different here and handles carbs differently. I know that @robstein and @MarkKO can drop fat while keeping their carbs as high as possible. I have not had such luck...although for me, cutting carbs is easier than restricting fat.
There are definitely protein powders with trace carbs, a gainer powder will typically have high carbs for the extra calories along with the protein.
When in a deficit I do exactly as you're describing. ALL of my carbs will be consumed peri-workout (which is usually evening for me). I'll have some carbs before, during and/or after and then meat/eggs/veggies/nuts/protein powder for the rest of my meals. Nothing fancy or revolutionary, but I don't think you'd be putting yourself in an awful position by doing so.
Depending on how intense your morning workouts are, you could possibly have a few carbs before bed to help make sure your glycogen stores are full upon waking, but that will likely be covered by your morning oats.
One of the best things you will do in your training career is finding what diet strategy works best for you, both when trimming fat and when trying to add mass.
I also wouldn't recommend Keto for only a couple weeks as most of that time you'll be in the adaptation period and you won't get the full benefit of it for the hell you'll be going through!
For me, these two articles is all I'll ever need for fat loss. Well, if I ever want to take my leanness to the next level, maybe I'll need some more help...but this can take you pretty far IMO.
And if you happen to slip a cheat day in there:
