Discussion on how to leave an agent

Hi guys!
I feel like this topic has been a little controversial every time I brought it up with someone, so I wanted to hear your thoughts.
Here’s my question : do you leave your agent before you look for a new one or after ?
Considering most contracts have a notice period (mine is 2 months). I’m wondering if I should secure a new agent, but might not be able to sign with them for 2 months, or just leave my agent first and then look for a new one.

For more context: I am with a smaller boutique agency and trying to find a bigger agency to move to an agent with a little more sway. I doubt that if I reach out before leaving my agent they would find the time and go out of their way to inform them.. my main worry is (if I’m considered) how would it be perceived if I tell them I have not left my current agent and need to wait 60 days to sign with them.