What was your question exactly? Do a search from last November, "stray dog pregnant or not". There may be a few headings like that discussing a litter due, whelping and puppy care.
Sorry, don't have time now, but there was a long discussion some time back regarding this. Couple if months? Try searching my posts. Average gestation is 63 days so calculate from the first breeding. Milk may or may not come in. Take temp twice a day, if she is close, and maybe you will catch the drop, looks like it us on it's way. Labor usually starts within 24 hours.