With a surprise party, perhaps, or a family meal? Or maybe a first legitimate drink in a licensed premises? For Andrew Holmes in Germany last weekend, it was the latter, but only after he had taken part in a row rated as the longest and most gruelling in the world.

Yet while the young Scot was still recovering from the 12.7km race a couple of days later, the 15 pints used to rehydrate after the event had seemingly left little effect.

“I was just a little bit drunk and I’ve not had a hangover,” Holmes insists of his birthday blowout. “The guys decided I should do 18 beers for 18 years and I managed 15 before I stopped but that was over six hours. That will be the only night out for the next few months because I’ve got a lot of hard work ahead.”

Indeed, the boy is having to adapt to life as a man very quickly.

Having started the year as a pupil at George Watson’s College in Edinburgh, Holmes harboured hopes of competing in the Junior World Rowing Championships in France but had few expectations of his potential performance. An impressive showing in the early months of the season earned him a place in the coxless four - Great Britain’s top boat at under-18 level – for August’s event in Brive but the subsequent gold medal and promotion to the under-23 squad has propelled him into the life of a professional athlete.

“Things have taken off a bit,” admits the teenager, who has recently moved south to Henley to be with the group. “Until the summer it didn’t really hit home how far I’d come but now I’m determined to see how far I can take it. I’ve gone full-time to fit in all the training sessions and I’m having to lift much heavier weights than before but I’ve just got to cope as best I can and keep pushing myself to match everyone else.

“Sometimes on a cold, grey morning you wish you were in bed but I read Lance Armstrong’s autobiography and he taught himself to love the rain and cold and make it enjoyable. I do sometimes feel I am missing out when all my friends are going out every weekend and now starting university but in the end I know it will all be worth it.”

It is a statement uttered with the conviction of someone older than 18, a fact Holmes attributes to his decision to move away from home at 15 to take up a scholarship in Edinburgh. Leaving Lochwinnoch, he insists, enabled him to not only dedicate himself to rowing but also instilled the self-belief and confidence to make the move south.

Not that he is ever short of encouragement or advice from his family. Martin, his father, rowed for Scotland at the Commonwealth Games and used to take the young Andrew out on the water “for a bit of fun and so I could splash around” but never pushed him towards the sport. Instead, he ferried his son to and from the various other pursuits in which he excelled in that infuriatingly easy manner enjoyed by natural athletes. A career in football was a possibility after he was invited for trials by clubs but he finally opted to emulate his dad and joined the local rowing club.

That, though, was not his only motivation. Rachel, his older sister, also demonstrated an aptitude for sport and enjoyed early success in both rowing and netball – she now plays for the Glasgow Wildcats and Scotland – which infused Holmes with a little bit of the green-eyed monster.

“She’s nearly two years older so things always happened to her first,” he explains of the sibling rivalry. “She got a bronze at the national rowing championships at 14 and wound me up about having a medal, so that got me going and I eventually got one as well. Then she was capped by Scotland at netball when she was 16 and it started all over again until I did the same thing and it was a similar thing with going to the world championships. It’s all in good spirit now, though, especially as I’ve trumped her with the gold.”

Holmes might just have more to boast about in the not too distant future. While he travelled to China last year to watch the Olympics – “I’d saved up money from my paper round to buy a car when I hit 17 but a couple of weeks before the games a few of my friends asked if I wanted to go to Beijing, so I thought ‘why not?’” – it is not inconceivable that he could be in London in three years time as a competitor if he maintains his rate of progress.

More likely, he insists, is 2016, but the plan is to give it two or three years full-time before reviving his plans to go to university and study engineering. An American scholarship is also a possibility but, more intriguingly, so too is a switch of sport. Holmes was selected to attend a national talent orientation camp earlier in the year and demonstrated such potential on a bike – taking just four seconds longer than Chris Hoy to sprint 1000m – that British Cycling wanted him to convert there and then.

“Maybe cycling is another option if the rowing doesn’t go so well, or even if it does,” he admits. “ Rebecca Romero showed that the two sports interlink quite well and speaking to a few of the rowers they talk of how boring it can get doing the same thing every day so switching might be something to consider in the future.”