I think this would depend on what your goals are (weight gain, cutting, etc).

During a weight gain, I log my weight once a week at the same time of day each time. I do check my weight before each workout just to make sure I am still gaining. If I lose weight during two weight ins, then I know I need more calories. Once you get your diet right, you should show a gain each week.

Pic wise, I do once a month but the way my clothes fit tell me more than anything else. If your waist gets to big, then cut some carbs and add more protein and good fats. I dont do a lot of cardio while trying to gain weight, I use food to adjust the fat gain. For me, carbs cause more fat gain than anything else. Remember this, your body cannot survive without protein or fats, but your body can convert fats to carbs.

If you are still at about 180 as you posted in your intro post, I would just worry about making sure you are gaining. Once you get around 210 or so, then decide where you want to go from there.

Dont obsess, just have fun lifting, eating, and resting.