<human>: Condense the text into a few key points

Hi /r/askreddit. Sorry if the title is a bit misleading, I don't actually have a job offer *yet*, but I'm preparing for what may come in the next couple weeks.

Over the last 18 months since graduating, I've had a hell of a time trying to find work in advertising. I have been interviewing with a small business for a position that isn't what I studied, but I am more than capable of. Right now it looks like I might be receiving a job offer from them in the next few days, which is great, because I need a job. Any job (and it doesn't hurt that I enjoy the industry I'd be working in.) We'll call this Job A.

In the meantime I have a lead with an ad agency who has produced notable work, and it would be beneficial to my resumé and portfolio in the long term, should I continue in the creative advertising field. There is no offer here yet, and I haven't even gotten an interview at this point, but there is still potential thanks to a direct connection with a top executive at the firm. However, with entry level positions at agencies, it's standard practice to offer freelance work, and not a "sure thing" position. Job B, here.

How do I decide which to pursue? Is there a tactful way to keep in touch with Job B, while accepting a job at Job A? Let's say I start Job A soon, I'll be working full time. How do I interview at Job B in the meantime? My fear is that I'll be working for two weeks, then suddenly interest from Job B will escalate - I really don't want to be an ass and quit or ask for time off immediately after starting a new job. Anyone who has experience with this situation, please weigh in! Thanks!
<bot>: Should I take a "sure thing" job, or risk it with another company that may or may not have solid work for me, but might be a better place to work for?