Heat stroke advice and worry need advice

Are heat stroke symptoms fast acting and noticeable straight away after too much sun and heat exposure or can heat stroke symptoms appear suddenly hours and hours after you where last in the sun and where exposed to heat? Like I had to walk a total of like 40 mins home in 24 degree c sunny weather with a navy teddy jacket on bc my hands where full I couldn’t carry it and also be on a 20 min hot train . It’s now 7 hours since I was last in the sun. I feel fine I think except I’m warm internally 36 degrees c body temp. I’m worried I possibly have heat stroke but I don’t know it yet.????? I’m panicking allot.