The most supportive thing I can tell you is that it won’t be easy. But nothing worth doing in life is really easy. Your whole life with your parents you probably just wanted control over your own life. Now you have control and it’s great. Once the dominoes are set up for your family, you no longer have control. You have influence, but not control. Go with it. Go with the flow. Nobody can fully prepare you, not even your own parents. Every pregnancy is unique, every relationship is unique, every child is unique. People giving advice about getting kids to sleep - they had sleepy kids and their advice probably won’t help. People giving advice about getting kids to stop crying, they probably had easier kids. Most people don’t write about unresolved struggles of parenthood.
Most people don’t tell you that newborn babies (0-3m) are the worst. It’s the 4th trimester and they should really just still be in a kangaroo pouch. Newborns don’t sleep at night. They exist on a 2-3 hour cycle of eating, sleeping, and excreting around the clock. When newborn babies are awake in the middle of the night, for the 3rd or 4th time, they’re not going to sleep, until the little 3 hour cycle is done. They don’t smile at you, or laugh. It’s really hard to support your zombie sleep-deprived partner. She won’t have any energy for your relationship. No sleep makes for short tempers - close to madness.
After that, it gets better steadily. Smiles, sitting, eating, crawling, laughing, climbing, walking, talking, hugging, loving, and lots of laughing.
Anyway, you will help your partner if you are a source of stable calm emotions. You’ll help if you learn when to step up, and when to step aside. Once you’re a parent you don’t have as much time for anxiety. You are just doing it, moment by moment, and you learn to go with the flow. Being a parent can only be learned on the job. By the time your kid is old enough to form lasting memories, you’ll already be a different person than you were before they were born, than you are now. You don’t need to worry about time, because you won’t have any. Well, you’ll have plenty of time I mean, but you’ll spend it on what’s most important to you - your kid.
Anyway, don’t sweat it. No matter how you prepare, you will be unprepared. Just do your best, and be your best version of yourself.