Sometimes yes, sometimes no.

Many, if not most, battles happened somewhat spontaneously, when one army made a stand at a particular place or after a lot of maneuvering. At Hastings (1066), King Harold's army deployed on a hill along the main road leading inland and waited for the Normans to come to them. At Crecy (1346), the French army had finally caught up to the English, who stopped to make a defensive stand. Agincourt (1415) happened much the same way. The Battle of the Spurs (1513) was essentially an ambush, as was the Battle of Jaffa (1192).

The Battle of Bannockburn was kind of decided upon before hand. The Scots were besieging Stirling Castle, and had an agreement with the garrison that the castle would surrender unless the English could send a relief force before a given deadline (by midsummer 1314). Edward II naturally raised and army, and Robert the Bruce was, naturally, waiting for him. Wasn't so much a "meet at this time and place" and more of a "we know they'll be coming here by this date, and they know we'll be here"

There were engagements, if not full battles, that were agreed upon by both sides. For example, during the ongoing hostilities between England and Scotland in the 13th and 14th centuries, there were agreed-upon "tournaments", sometimes in conjunction with a siege (such as the siege of Perth or at Alnwick Castle).

Most of these "jousts of war," or jousting à l'outrance (under battlefield conditions with battlefield weapons) were small affairs. One example would be the Earl of Derby and three of his followers verses William Douglas and three of his followers in 1341. They jousted à l'outrance. Douglas was killed.

One of the largest was again organized by the Earl of Derby against Sir Alexander Ramsay at Berwick. It was 20 vs. 20 (not in one big melee, though, it was a series of single jousts spread over three days). At least 3 knights died of their wounds, and several others were wounded, including Ramsay. The accounts of the event generally describe the two sides being generally cordial and rather "comrade in arms" with each other, inviting each other for dinner and awarding prizes for bravery and valor.

/u/Vromrig wrote an excellent answer to a similar question 2 years ago.

TL;DR (which doesn't remotely do it justice):

• Armies in marching columns are vulnerable (as evidenced by successful ambushes throughout history)

• Armies prepared in battle lines are safer, naturally

• Therefore when two armies are coming into close proximity for whatever reason (perhaps detected by their scouts, or local intel), the commanders will be inclined to prepare battle formations, and edge towards a battlefield that suits their strategy.

As for the commencement - it would depend a lot upon the situation. For example at [Garigliano](https://en.wikipedia.org/wiki/Battle_of_Garigliano_(1503)) in 1503, miserable weather had both armies sitting across the river from each other for six weeks.*

Sometimes, as in Battle of the Bastards, there would have been diplomatic meetings prior to the battle, perhaps with each party trying to achieve satisfactory terms and preserve their army. But as Vromrig said it was more likely a matter of the commander's initiative - deciding if it was the right time & place to attack.

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*Montgomery also writes of this situation:

At Christmas there was a two-day truce, and some fraternization took place between the armies - the French soldiery continuing their celebrations for several days.

Heheh.

The full Spanish attack then commenced on the 29th, and they won a solid victory, presumably as the French were hung over from their continued revelry.