One thing she did a lot was saying I-I-I, just repeating the word "I" at starts of sentences. She does that still occasionally but not in a way that is conclusively from a stutter. She was also having straight up blocks and repititions with consonants as you describe. All of that just resolved on its own though, no intervention from a speech therapist at all. We did inquire about it though and were recommended to hold off on anything at the time. Sorry you're feeling uneasy about your child's speech. It's good you are addressing it now! Probably it'll be mild but as someone who has a pretty severe stutter at times I know everything can still work out great.