The answer to your question may be found on the website below. I have used this particular website with my 5 year old son many times to begin to learn words that he will need to know in kindergarten. He particularly likes the Cat and Mouse spelling game. This site's features are free, though if one wishes to subscribe for further features, one may. It is great for sight words and spelling lists, alike.
I am an early childhood literacy teacher and have taught for 29 years. We need to understand that children vary in their developmental levels. Young children will demonstrate a wide variety of skill level. Some four-year-olds, and even some three-year-olds, might be early readers. Some children may not read until age 7. And that's ok! My daughter wasnot developmentally ready to read until the end of first grade/age 7. They even sent her to the reading specialist starting in November. The RS said she was just immature, did not have a learning disability. Reading is a complex process that can only develop when important foundational skills are in place. We need to give each child the time s/he needs to develop those skills. We need to accept that the age for learning to read is 3-7 years old. So we can expose kindergarteners to sight words and we should. But we should be careful of our expectations. And we should assess emergent literacy skills and use that datato inform differentiated instruction, it is not one-size-fits-all. My daughter had no sight words mastered at the end of K. But she loved books, stories, language, word play, her name. That's just where she was at. Her brain wasn't ready to store symbols, letters and words. So we can't put a number on it. The answer is "It depends on the child..." All children should catch up by grade 3 and be on grade level for reading. My daughter is now in fourth grade and either on grade level or above in all of her readong and writing skills. There was no reason to panic! Observe your child and follow his/her lead.