My boyfriend leaves everything to the last minute and forgets plans. How do I address this?

| [19F] need advice on a recurring issue with my boyfriend [18M]. We have been together for 5 months and he has a non-stop pattern of leaving things to the last minute and forgetting to follow through on plans unless I constantly remind him.
This isn't a one-off thing—he does this all the time.
For a recent example, on Monday I invited him to stay over this upcoming Sunday and Monday. He said he would ask his family later that day to confirm. It is now Wednesday, and he still hasn't checked or given me an answer.
I really hate last-minute planning, and he is well aware of this. It's incredibly frustrating to constantly feel like I have to nag or remind him just to get basic information about our plans How can I effectively communicate to him that this behavior is frustrating without feeling like I'm managing his life? Any advice on how to set boundaries around this?
TL;DR: My boyfriend [18M] of 5 months constantly forgets to follow through on plans and leaves everything to the last minute unless I [19F] nag him, and I need advice on how to set boundaries without managing his life