I've got a late middle-age like world, with a situation similar to Europe/America: one continent has a technological advance, and enough sailing skills to discover the other continent.
The incentive to sail however is different: Columbus discovered America while searching India. In my world, it's diferent: trade is quite developed on the continent (wich is much smaller than Eurasia), and planet radius/distance is well calculated. I am not looking for a trade route with the east of my continent, but for lands. I just have some ships that can't trade with the lands in the east for some geopolitical (or other) reason, and decide to take the risk to make them sail west. Other countries could maybe find the other continent, but it seems that they just use ships to trade in known routes/lands. There have already been some expeditions west in the past, but they either returned without a discovery, or never come back. My kingdom is in west coast, usual trading route follow the coast by the south, until reaching the east of the continent. Instead of heading south following the coast, the ship just go straight west. As my kingdom is on the west side, the ship was never close to a neighboor kingdom coast.
And here is what happened: one of the ships I sent several month ago just came back. It seems that my kingdom just discovered a new continent. That's great! I could try to learn more about this new land and the people there, even trade, establish trading posts, or even a new colony.
However, I'm afraid that neighboring kings will do the same. I don't have a good army, not even a really good fleet (sure, my boats are great, but I don't have a lot of them). What I would like is to make profit out of this new continent - alone.
Which methods can my kingdom use to delay the discovery of this new continent for as long as possible?
Answers should provide an estimate about how long it will take others to discover the continent if I go along with their proposed methods. Answers can include details about how the first expedition should have been done.