How long before muscle shows on the scale?

Azdak

Weight loss is not linear. In addition to whatever fat oxidation (loss) occurs, there are also ongoing fluid shifts and variations in fuel storage, among other things. This means that scale weight will often proceed in more of a zig zag pattern. My loss went more like a scallop pattern. Every time I reached a new "low", I would inevitably "arc" up 1-4 pounds and then drop back down, often to a new low.

If you have been on a program since Jan 1, you are still adapting to the routine. It is way too soon to see any increase in muscle mass. The fact that you dropped 8 lbs in the first two weeks suggests you are following a minimal calorie diet which just enhances the shifts described earlier.

Chances are any increases in muscle mass will be modest. I would not look for substantial changes in that regard, esp in the initial weeks. If you are eating 1400-1600 calories a day, I would not be overly concerned with eating back exercise calories. After longer or more intense workouts, it can be helpful to eat a "refueling" snack or small meal afterwards--at this point, that is more important than trying to "eat back" all your exercise calories.

You are not in any so-called "starvation mode". You do not need to vary your program (any more than you already are) in order to "shock your body". You should be sticking to a good, focused workout program that includes some endurance workouts, some medium tempo workouts and 1-2 harder interval workouts, along with a couple of strength training sessions per week.

Stay consistent and you should see results. Down the road as your body composition changes and fitness level improves, it will be necessary to make some adjustments, but you can deal with that when the time comes.

It would be a good idea to take some circumference measurements for future reference.