I didn't really know what a sutta was until I'd been involved with Buddhism for a year or so. I just went to the Wat, chanted, had lunch, helped in the garden and eventually (a few months later when an English-speaking teacher turned up) had some meditation instruction.
Subsequent reading of suttas confirmed that the teachers were actually practising and teaching in accordance with the satipatthana sutta, and other suttas (noble truths, eightfold path, anatta, obvious bits of dependent origination, hindrances, faculties... ) and, like all teachers, their instructions were an elaboration of certain points in those suttas. [In the case of my teachers the elaborations were from the Mahasi school.]
The experience that really convinced me that what was communicated in the suttas was from real knowledge was when I was sitting a Goenka retreat a year or so after I'd started serious meditation. By that stage I'd read In the Buddha's Words
and was working through Bhikkhu Bodhi's talks on the Majjhima Nikaya. I recall sitting though (naturally) all kinds of hindrances and realising that the similes in SN 46.55 of the hindrances as water in a bowl obscured by dye, boiling, weeds, ripples, and mud really did describe what I was experiencing. (Strangely, that sutta is hard to locate on line, though the similes are in a Wheel publication by Ven Nyanaponika: The Five Mental Hindrances and Their Conquest
Did I get any "instruction" from suttas? Not really (and obviously not at all at the start). I did get confirmation that the instructions were on the right track though, which is good to know...