Moving a large amount of cash gradually?

I (26F) currently have €18k invested and €52k in savings. I want to invest more of my savings, but I’m not sure how much to move into the market or what the best way to do it is. The idea of placing a €20k+ buy order makes me nervous lol.

For those who built up a sizeable cash position before investing, did you move the money into the market all at once or gradually over time? If gradually, what schedule did you use and why?