I am currently surrounded by multiple "friendly" and "cordial" empires who have not yet realized that ultimately their conquest through me is inevitable. But it might still take a few decades until I will start my galactic conquest.
However, I noticed a new game mechanic in Update 2.0: I can "Make Claims" on their territory, which costs me Influence but apparently is a prerequisite for claiming their worlds when I declare war on them.
Does it make sense to make those claims now or should I wait until I am about to declare war? What happens if they declare war first and I don't have any claims yet? Can I still make them or am I out of luck? And will making those claims hurt my relation with them?