My meal planning is pretty relaxed now. I used to plan for 2 weeks at a time with definite days for each meal.
What I do now: I take a note pad and write down 5 dinners I’d like to have in the coming week. I’ll normally include side dishes ideas at the same time but it can be pretty vague: salmon with rice and greens, fajitas, slow-cooked pork masala with rice, cannelloni and caesar salad. I normally look at the sales flyers while doing this, I don’t necessarily try to get only on-sale items but often it’ll give me ideas. “Oh, blade steak is on sale this week, let’s cook one in the slow cooker with winter veggies, we haven’t had that in ages”, type of thing.
Now the hardest part: Once I have my list of 5 dinners, I make a second list (my shopping list) of what needs to be picked up at the store to make those 5 dinners. Most of the stuff I cook I know off the top off my head what goes in it and I normally know what I have in my fridge and pantry. Sometimes, if I’m making something a little more elaborate, I’ll dig out the recipe and double check what needs to be purchased and what I already have on hand. I say it’s the hardest part but really, it never takes more than 5 minutes to double check what we already have and what needs to be bought. It’s just the getting off my butt which was on a chair while I was writing down the menu that’s hard.
So now I have 2 lists: one with the 5 dinners (our menu) and the other is the shopping list. The shopping list will have items on it like: Green veggie to go with salmon, veggie to go with pork masala. This gives me the flexibility to pick what looks best at the grocery store.
Next I add to the shopping list any household items we’re running low on and stuff for breakfast and school lunches (I bring dinner leftovers to work for lunch).
Now you can finally go to the grocery store.
I leave the menu list in the kitchen in case I forget what all those things in my fridge are supposed to be combined into. You could get fancy and write each individual dinner menu on small post-its and stick them on your calendar. Post-its would be good since you can move them around.
That’s it. I come back from the grocery store and I know, with confidence, that I have food in my house for 5 dinners. I only do 5 because I know life may get in the way and we’ll eat out once, or not feel like cooking and have breakfast for dinner or have leftovers for dinner one night. Worse case scenario, 5 days later, I start the process again.
As to when I eat what, it depends how we feel the night before. That's normally when I'll decide what is to be eaten the next day in case something needs to be thawed or soaked overnight. If I know it will be a busy day, I'll plan to have one of the quickest items to cook. If I know I won't feel like cooking at the end of the day (seems to be recurring every Saturday for me), I'll go with something that can be prep'd ahead of time like a slow-cooker meal. Sometime, it's also just because I know the kale will be bad if I wait one extra day, so it should really be eaten.
I hope this gives you a starting point!