You matched with someone you are actually excited about, which means the first message now feels like a job interview. It is not. It is one light touch whose only job is to start a back-and-forth.
The bar is lower than you think, and also more specific: not impressive, just easy to answer and clearly written for them.
Why "hey" gets nothing
"Hey" is not rude, it is just empty. It hands the other person all the work: they have to invent the topic, the energy, and the reason to care, on behalf of a stranger. Most people will not do that job for you, so the match sits there until it expires.
The fix is not a canned opener either. Anything that could be pasted to fifty people reads exactly like it was pasted to fifty people. The whole game is showing you looked.
Find the second detail
Whatever is most striking in their profile, the marathon, the golden retriever, the trip to Japan, is the thing every other match already commented on. Skip it, or come at it sideways. Look for the second detail: the background of a photo, a throwaway line in a prompt, the band shirt, the strong opinion about pineapple pizza.
Commenting on the second detail does two things at once. It proves you actually read the profile, and it starts a conversation that is not a rerun of the five other ones they are having.
“everyone's going to ask about the marathon so I'll ask what matters: what's the story with the inflatable dinosaur in photo four”
“your answer about switching careers at 30 got me. what finally made you jump?”
“you have strong taco opinions in your bio, and I have a spot that would change your rankings. this feels like something we should settle in person”
Make it effortless to answer
End somewhere easy. One question, not three. A question that is fun to answer beats a question that is thorough. "What's the story behind X" almost always works, because everyone likes telling the story behind X.
And match the length of the profile you are messaging. A three-line opener to a profile with one-word prompts is over-investing before you have even said hello. One or two sentences is right almost every time.
Sound like you, on a good day
The opener's job is to start a conversation the real you can continue. If you write something a smoother, different person would send, you have signed up to impersonate that person for the whole conversation, and the first date becomes a reveal.
This is the AfterSwipe rule for every reply, first message included: your voice, true facts only, no lines you would cringe at later. Charm you cannot back up in person is not charm, it is debt.
Common questions
Who should message first after matching?
Whoever wants the conversation to exist. On Bumble the choice is made for you. Everywhere else, waiting around to avoid seeming eager mostly gets you expired matches. If you were excited enough to swipe, send the message.
How long should a first message be?
One or two sentences. Long enough to show you read their profile, short enough that replying feels effortless. Save the paragraphs for when the conversation has earned them.
Are pickup lines a bad idea?
Canned ones, yes. They tell the other person you are running a script, and the reply you get, if any, is to the script, not to you. A specific observation about their actual profile beats any line ever written.