If equity is available, then buy immediately. The time until construction starts can drag on and you would already have to pay interest on the withdrawn portion and would realize during the planning phase that the original loan amount was completely miscalculated. All avoidable. The bank will later value the €90K plot of land in your possession as €90K cash in your account, provided it is not an absurdly overvalued purchase price of the land and the value is actually lower.
Great help and information. I think I will do it that way. Very helpful.