First of all, relax, it’s never too late and you can easily catch up within 4-6 months and be in a good position for applying.
If you are not clear on DSA, would recommend you to pick a course out of so many available on the internet and complete that first. If you did study in college, but don’t remember, brush up on the college notes or read about various topics from GFG.
Then for practise start by doing a list of questions topic wise. You can follow interview bit buckets or Leetcode150/Grind75/Blind 75 on Leetcode. This is to cover all the topics and give you some confidence.
Then start doing random Medium and Hard LC questions. This will be tough initially because deciphering what Algo or Data Structure to use takes time. Stick to it, if not able to think of a solution to a question within 15min, look at the answer. 100 questions or so should be enough more or less to get good control and confidence. You can practice more on topics you struggle with.
When you feel confident, start applying. Have patience throughout the process. All the best!