How long should I wait to get a text back without seeming needy?

Hi, so there is this guy I really like. We been really hitting it off and I am scared to fuck things up because of a few reasons. I won't list them all but I will say is that I know, I am a very needy person. I naturally get insecure if I don't hear from you but I AM WORKING on it. I try and tell myself good thoughts and keep busy when I am waiting. Because it caused so much anxiety on my exes, I finally am trying to learn from my bad behaviors before. However I am clearly needing to work more on myself because I am starting to get insecure with this guy. I have not told him anything because I don't wanna scare him but he has withdrawn. he texts less often and his replies are so short. When we met he would text a lot and sometimes he would send me long ass paragraphs that I would take 5 minutes to read. I dunno what has changed but I am feeling worried. Part of me wants to rationalize this fear because clearly he's different and that could be a sign of something is going on. But part of me knows from my past is I overthink every little thing, even the change in voice. It's been 3 days since I last heard from him. He doesn't know I get scared when he takes awhile to reply. How long should I wait and give him space before I should send him a new message? I don't wanna be that "needy" girlfriend again. and No I don't want a guy who wants to be with a needy person. I know they are out there but I really don't think it is healthy for me to indulge in this side of me.
How long should I wait to get a text back without seeming needy?
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