You have 54 days to complete 5 royal quests. First, set out for a new journey. It is best to pick a location closest to Ascala - they are easy to complete and enemies aren't demanding. The only obstacle may be the fact that your party is made up of fewer than four companions and you may be outnumbered by the enemy. However, try to use your resources effectively - send Signy to battle and put her in position that will allow her to deal damage to groups of enemies. You can use Griffith to taunt enemies, which will keep the larger enemies occupied. Remember that you can revive your party members in camps, during the journey.
As soon as you end the journey, new events will occur in the kingdom. A merchant and a mysterious woman will appear in the city, who will soon introduce herself as Aliss. It will turn out that she wields magic. It's perfect, because your party will make use of a ranged character. Include her in the party and set out for another journey. This time around ,it is going to be even easier - against the four of you, enemies should stand no chance. Apart from that, you will receive new gear for your party, as well as experience points, which will additionally strengthen the party.
At this point, take another journey. There is no point in wasting time and new events will have place anyways, in the background. Just like earlier, it is a good idea to pick locations near the city. Spend some time on learning how to use Aliss's skills. Especially the last one. The summon is very strong and it is definitely a good idea to use it in battles. As soon as you complete three journeys, return to the city and sell the items you don't need.