In the first 1,500 words the MC meets a goddess and fights her. I'm worried that it's too sudden and doesn't give enough time for the reader to get into the story.
Agreed with @OJB. A well-written fight could be a good hook. If fighting a goddess is a thing that's possible in your setting, opening with it is certainly an interesting way to introduce that setting.
My wip has action in line one - tbh in a thriller/adventure/action book you want excitement or tension straightaway to hook the reader
Depends on what you mean by "action." Not every story needs to have car chases and explosions. I'd say it's important to have conflict, if not on page one, then definitely by page two. What that conflict is, how it relates to the central conflict, and what actions the actors take to resolve it will depend on the type of story you're writing.
@Songshie Well that is dependent on how soon you need the action to kick in. If you feel that it is too soon, then add a bit more to the story or start it up in the second chapter. Sometimes you need to build up to events a little to get a better payoff of them, before you ease the reader back down. Though how do you plan to out do fighting a goddess so early on? Pretty intense stuff right off the bat, that will make anything else seem less so in comparison.
"So you want to fight a goddess, obviously you hit her round the head with a potato in sock while she's looking the otherway. It's no big deal really goddesses are easy, they think they are so special that they always overlook the potential for a sneaky mortal with a jersey royal to sort them out. Goblins on the other hand, now they really are nasty little bastards... there was this one time... "
If you're going to start it big, remember it should be just a teaser for what's to come. Cut it early.
This all depends on context. How long is the WIP going to be when it is done? 2,000 words? 20,000? 200,000? I can keep tacking on zeroes, but you get the point. What is the main conflict? Is defeating this goddess going to be the climactic victory of the story? Who wins? The goddess, or the MC? Do we get to see the MC fight before she fights the god? In general, I think you're going to want to either push the fight back, or else have a cold open that begins with her fighting the goddess. If you want to establish that your MC is super powerful *before* she fights the goddess, you're going to need time to explain that, but if you want to establish that your MC is super powerful *because* she can fight the goddess, then you want to introduce it right at the beginning. That's all dependent on context, though.
There is only one thing you should be concerned about here. Will the reader care about what they are reading? The idea that action itself is automatically 'exciting' to read is a mistake. It's not, if we don't care. In fact, I often find myself skipping over action scenes in books I've just started, if the action scenes come before I've become engaged with the story. I just get bored with them. Something about any action or fight—wherever it comes in a story—has got to make me sit up and take notice. What's at stake in the fight? Does winning or losing bring major consequences? Do the fighters know this? Is there something unusual about the fight? (Would I be intrigued by a rabbit holding off a hungry pack of wolves simply by glaring at the alpha wolf out of two clicking green eyes? You bet I would.) A sense of personal jeopardy is also a good hook, but we need to feel what the POV character feels. That's not going to happen by simply describing where they stand, how they swing their sword, how blood spatters, the ground, how the opponent takes a whack, how the POV character whacks back, and the opponent ducks, etc. You need to get inside the POV character's head as well. I keep citing it, but the best opener I know of, that starts with combat, is the opener to Joe Abercrombie's First Law trilogy, the book called The Blade Itself. If you haven't read it, go to the book on Amazon and read the 'look inside' feature. It's all there.
What @jannert said. What happens to make us care? Suddenly I'm reminded of the British TV series Coupling again. Jeff is referring to the movie The Blob, and blurts, "Oh, god, yeah, and there's always this puppy trapped in a car that you've got to rescue!" To make us care this early, you may need a puppy.
Yes indeed, the opening scene in The Blade Itself was excellent... but oh how I lost interest in that story by 2/3 of the way. I had heard such great things about Abercrombie, but in the end the story felt derivative, though at least it was good derivative. I think I've just had enough of white guys thrashing about with swords. I need more than that to keep me engaged with a book.
You could start with an action scene that isn't related to the Goddess vs. mortal thing also, either to show the mortal's fighting prowess (or lack thereof, if there's training involved later on), or to show that gods/goddesses do face mortals from time to time, and put them away handily. This will a) open big, and b) do a little bit of worldbuilding for you. I know books and movies are different art forms, but think of James Bond; they always open big, and people have come to expect that.