Short answer. Five days. Article 66 allows any aggrieved person to appeal the decision of the authorised agency of the Department of Labor and Employment to the Secretary within five days from receipt of the decision. The Secretary's own decision is then final and executory.
What the law says
The decision of the authorized agency of the Department of Labor and Employment may be appealed by any aggrieved person to the Secretary of Labor and Employment within five (5) days from receipt of the decision.
Labor Code, Article 66 — Appeal To The Secretary. Read the full provision →
The clock starts at receipt
The five days run from receipt of the decision, not from the date written on it and not from the day you understood what it meant. Those can be very different dates, and the gap is where appeals are lost. So the first thing to establish is the day the decision actually reached you, and the second is to be able to prove it — the envelope, the registry return card, the transmittal or the covering message. Five days is short enough that a week spent looking for the paperwork is fatal on its own.
Who may appeal
The provision says any aggrieved person, which is wider than the parties who filed. An apprentice, an employer, and anyone else the ruling actually operates against may take it up. What the phrase requires is that the decision harmed your position in some concrete way; disagreeing with the reasoning while getting the outcome you asked for does not make you aggrieved. If your interest in the matter is indirect, that is the point to raise and explain in the appeal itself rather than assume.
“Final and executory” is the end of the road
The article closes by making the Secretary's decision final and executory. That is why the five-day window matters so much: it is not the first of several chances but the only step the article provides, and after the Secretary rules the administrative process is over. Treat the appeal as the place to put your full case rather than a holding step. Anything you were saving for later — a document, an argument, a correction of the facts as the agency found them — belongs in it.
What to do in the first day or two
Write down the date of receipt while you still remember it and keep whatever proves it. Read the decision for what it actually decided, which is often narrower than the dispute you brought. Gather the documents the ruling turned on, especially the apprenticeship agreement itself and anything showing what was agreed about wages, hours and the period of training. Then get advice immediately rather than after preparing a draft; with five days, the sequence matters as much as the substance.