plc'r'us - here in the UK ( nd I guess your systems in ESP could be similar) there is no defined time that a SMS text message will be delivered. I have heard stories of up to 24 hours at peak network times, although I have never experienced anywhere near that lag in SMS delivery. In my experience 0 to 2 hours is the norm.
I learnt a couple of years ago that some mobile networks can sell you a subscription service that enables your SMS to jump the queue, and virtually guarantees delivery within a specified time.
It all depends how important your SMS is.