hello    I invested in my first pair of proper grown up boots about 4/5 months ago and just wanted to check when should they be resoled. They seem to have 3 or 4 different layers of sole and i wasn't sure which layer would be the point of no return so to speak. is it the layer i'm currently working through or can i keep wearing them once I'm walking on the darker layer? sorry for the bad photo, best I could do