A date idea can be a night out or something simple at home. Write it down when it sounds good, without needing to choose a day immediately. A shared list works well for this; add enough detail that you will remember what you liked about it later.
When you both like an idea, put it on the shared calendar with a day and time, and choose who will arrange it. The plan shows up for both of you, so nobody has to remember it twice.
A plan is not a booking. Check opening hours, prices, and availability with the venue before you commit. Tiptoe does not reserve a table or buy tickets for you.
Keep a surprise out of shared places. Private gift ideas and private tasks stay yours, so the details stay hidden until you are ready.
If nothing on the list fits, pick something small. A walk and takeaway coffee count. The useful part is making time that works for you both.