No need to talk to them before demo day but you can add them to your investor update list for when you’re 5 weeks to demo day and then you’ll have a lot of good news to share to get them interested.
If you don’t need the money, explain you aren’t fundraising right now but can schedule a meeting in the window 3 weeks prior to demo day and demo day. If you have an angel that is insistent, you can send them a SAFE they can invest in you on now if they like but explain you can’t meet until that scheduled meeting date.
So if there is an investor that just wants to fund you send them the SAFE and if you have a deck you can send them but don’t meet and explain you can’t meet until that allocated time. Fundraising is best when you do it intensely and in a concerted way if you have enough cash now. If this is not clear, for a fund if you have enough money now just reply back and schedule a meeting for January.