It's not terribly difficult to train yourself, if you care about the doing. If you care about selling yourself more, BICSI will happily take your money as a certifier. Probably better if you can get your employer to have you certified as continuing education so BICSI can take their money, but if it's not applicable enough to your job, it's not.
When I was teaching myself (for work, but the budget was low) I managed to attend a quasi-local fiber optic conference which had lots of BICSI training classes as part of the offerings (but attendees could attend regardless of affiliation - BICSI members would get their cards stamped [or equivalent] to prove they had kept up with training classes.) I've also done some online training webinars under the same circumstances.
As someone new to fiber optics who had actually read and understood the basic background information, I found that there was very little new content to most of these training sessions (and many of them were not-so-subtle sales pitches for some company's product, yet they were an approved training class.)
I remain unaffiliated with BICSI, but I built a fiber optic network that has been running for 6 years now with few problems, and at a very attractive price for my employer. But I don't have any certificate for that...
By the way, if you are talking about "custom length patch cables" rather than fiber in walls or between buildings, I can save you the bother - the industry-wide recommendation is to order those factory made, it's almost always a better cable that's more cost effective. Concentrate on remembering to inspect and clean before every connection, and put your initial educational effort there.