For anyone trying to teach their kids to read at home, let me highly recommend Bloomfield’s book Let’s Read, from the 1960s (original; more recent edition). Some of the stories are a bit dated with a mid-20th-century-American perspective on gender roles etc., but apart from that it’s the best way to teach reading that I have seen.
Bloomfield was one of the top expert linguists in the world, and he developed it for teaching his own kids. The first 150 lessons or so in the book use only regular spellings, so that the sound of a word is completely predictable. Each lesson focuses on only one new sound or spelling, and with only one new thing to learn each time, there’s a lot less confusion than a typical basic reader. Only after that solid foundation, which gets a kid up to several thousand words, are irregular spellings introduced, a few words at a time. The sentences and stories do a great job of mixing previously learned words in occasionally (cf. spaced repetition) so that kids won’t ever have trouble forgetting what they learned in previous lessons.
My just-turned-4-year-old has been doing about 1 lesson per day (each takes 10–15 minutes) for the past ~8 months, and is now almost through the book (245 lessons total) and has gone from only knowing the alphabet up to reading at a typical second grade level, and still continuing to rapidly improve. He can basically independently read anything up to the limit of his attention span at this point, and it took very little fuss or pain.
Some of the early lessons take a bit of struggle but they’re within the limits of typical kids’ focus/attention (if the occasional lesson gets too frustrating, just stop and come back another day); depending on the kid I’d say start anywhere from age 3 to 7 years old. The vast majority of 5 year olds will be able to handle it without much trouble, with adult support.