The period from first contact to first cash request could be a few days or a few months but regardless how long you've "known" the person, a request for money is a scam.
Scammers operate from countries with low per capita income and even if a scam takes months to pay out it is worthwhile for them, even for just a few hundred dollars.
Rather, I want you to take responsibility for your own actions. What if, it was only within yourself that it could possibly change?
Could this dating spam have come from your boyfriend's former adult dating site use?
It's possible, yet more likely that your cell number got thrown into some database somewhere (similar to emailed internet dating scams).
I just block them, try to use fake numbers if I have to when signing up for things that "require" a number, and leave it at that.
If it becomes an ongoing issue, I'd likely call my local authorities to see what I could do on a more formal level.
At this point she will set the victim up as her knight in shining armor, the only one who can help her.
She might just need money to pay her bills but will probably want desperately to come and visit him in his Western nation.
The other possibility in your situation might be that your boyfriend left his own phone somewhere, and you grabbed it, saw the dating spam, and were confused as to where it came from.
This is a much more serious situation - but not why you might think.
Scammers use services like Western Union because it is all but impossible to track the recipient of the money which can be picked up anywhere in the world.
A scammer could be a man or woman operating solo, posing as an attractive young lady, or part of an organized scamming operation.
Your email (which was much more lengthy than I could share here) detailed a history of trust and commitment issues between you and your partner.