most all plants will show preflowers by the 6th week of veg especially if a 18/6 light cycle is used(some sativas could take a bit longer). the longest a plant has ever gone in my grows without showing preflowers was 7weeks and it was a bogglegum male. it is not just autoflower strains that show preflowers. i am very suprised that your ww's haven't showed at 120days. they must be monsters! the nodes are alternating, right? in my experience preflowers come before alternating nodes. post some close ups of the nodes if you can especially nodes on the main stem. i suspect that if you look hard you will find some. i just can't believe a plant would go 4 months without showing sex!