Its not horrible to wait 24 hours to start war but it would be cool to have a Ready button that the entire team can click individually to let the leader know everything is done and ready to go and give the leader a main ready button that if selected on both sides will force start the war but only if the whole has selected they are ready!
Please use the search function in future as this has been suggested before and I don't think this would work out that well but you never know with Supercell.