I have one with first transaction back in 2012: 1HZwkjkeaoZfTSaJxDw6aKkxp45agDiEzN
Message: "Oldest i have"
Signature: "HJhVCVulX2Ezm8441dwXgay67ozUB3Zx7ugZ+uIjxGI5ad1+9D7jkFvHIHl+7vCS5w9FCDoyVdzxAj8NVGDSrJE="
I've posted a signed message with a bitcoin address here 3-4 years ago just in case my account gets hacked.
I'm too lazy to search for that post and I don't see any point.
I don't know if I still have control over that address,though.