Hi there, and welcome to the forum. There's a wealth of information here, if you look hard enough.
I suggest you read, under the "Understanding FICO Scoring" major thread,
"Credit Scoring 101 - START HERE!"
To answer your first question, as a credit score is a snapshot in time, it gives you a picture at the time the CR was pulled. It could change daily, depending on many factors:utilization, credit limit increase or decrease, rate increase or decrease, the aging of any lates or any other 'baddies' that may be lurking on it, to name a few.
There is no predictable way to foresee these things that I know of. Sorry.
I'm hesitant to answer your 2nd question. I'm sure others with more experience than I can answer it though.
"Never ever, ever be late. Never"