Just out of curiosity, what is the general timeline for gravid females from fertilization to birth? (like, how long) Also, how long until you can generally definitively tell they are gravid?

Mainly I ask because the scar tissue from Harley's surgery last year causes a long section of her abdomen to look like it constantly has scale spread (and will probably look like that till she sheds... It's been awhile since she shed, but her skin still looks good) so I'm thinking it'll be difficult for me to tell she's gravid for sure until near the end. We don't have a gram scale, so I can't weigh her.