I've done some research on google, looking up 'healing time shallow stab wound' and this pdf (
http://docs.ksu.edu.sa/PDF/Articles01/Article010858.pdf) on wounds and their legal and medical classifications. I also looked up the tattoo tags and checked ljseek for 'stab, wounds.'
So, in a way, I actually have a couple questions here. First, to set things up.
The story takes place in a modern setting, but mostly in a rural Mexican backcountry. A relatively young and healthy male gets involved in a knife fight, and in the process, his opponent strikes a blow squarely on his heart. Thankfully, this lucky schmuck happens to be wearing a wooden scapular (a small catholic devotion necklace) that catches the tip, breaks it, and stops the knife from stabbing too deeply at his heart. A doctor patches the guy up and he goes back to his village to recuperate.
So the question is, for something like this, where the wound definitely required some stitches, and might've gone deep enough to hit the ribs (or at least bruise them I imagine) how long do you think the healing time would take before the wound is at a 'barely started scar'? Or, conversely, for it to be healed enough that he can start getting a tattoo around it? Pain isn't too much of an issue, and he's probably not going to get too much work right over the wound, especially immediately. But having the whole thing get pussy and gross is also not fun. The beginnings of the tattoo would probably be started in a traditional low tech way rather than with contemporary machine done work, as well, but he'd still know enough to keep everything clean and disinfected.
The pdf I linked cited three weeks as a time frame for a general incised wound to heal over into a red scar, and I could work with that, but I figured it was worth asking for expertise, since that was the ONLY source I had found. Especially with the addition of a tattoo in the mix.
Sorry for the long post, and thankyou so much for any help you can offer ^_^