Shii-Cho (Form I) is normally the opening form for most Jedi, as it was originally developed as the bridge between traditional bladed weapons and the lightsabers and gave the basis for all other forms, the fundamental movements of which all derive from this form. After that Soresu (Form III) and Ataru (Form IV) were the most commonly taught, with the former specialising more on defense while the latter gave more aggressive options.

Niman (Form VI) was developed as a fallback for those Jedi who showed little skill with a lightsaber, focusing instead on easily performed maneuvers which would allow a Jedi to instead focus on their use of the Force, combining telekinetic attacks with their bladework. While quite common it was not as widely taught as Soresu or Ataru, and some viewed Niman a sign of failure as originally only those weak at Shii-Cho were trained in the form. However after the Old Sith Wars ended (297 years before the Sacking) the form took on a more spiritual significance as its practitioners were seen to have a stronger bond with the Force than other lightsaber forms.

Shien and Djem So (both later combined into Form V) were developed in parallel, with the former specialising in ranged defense while the latter dealt with close combat blocking and counter-attacks. This form was considered a refinement of Soresu and taught to Jedi who showed a more balanced nature than the more defensive practitioners of the earlier form, as it gave the option for refined attacks while still having a strong emphasis on defense. As specialist forms Shien and Djem So were considered unusual at the time of the Old Republic, although were still common enough to be taught regularly at the Jedi Temple.

Following the Great Hyperspace War and the Old Sith Wars the Makashi form (Form II) fell out of practice, as very few lightsaber wielding opponents in the galaxy made the sparring form of use only against other Jedi. By the time of the Sacking only a few Masters were available to train new students in the form and although the return of the Sith made the form greatly desirable, few managed to attain any level of skill before the Sith invasion.

The least common of all forms was the Juyo form (Form VII) which was highly aggressive and required practitioners to access the darker sides of their nature in order to perfect, something many within the Jedi Order maintained was a bad compromise for the unarguably more powerful aggressive attacks the form taught. It should be noted that most Jedi who turned to the Dark Side during the relatively peaceful years between the Sith Wars had, at some time or another, studied the Juyo form. Much later a new form, known as Vaapad, was developed by Mace Windu in order to overcome the dangers of the Juyo form, but out of the four known Jedi Masters to study Vaapad only Mace Windu never fell to the Dark Side, while Quinlan Vos managed to return to the Light after only a short period under the influence of the Dark Side.

Basically all Padawans would've been taught Shii-Cho initially, and only later would they specialise into another form more suited to their temperament, achieving mastery in their new form rather than continuing their studies in Shii-Cho. Most Jedi Knights would've been expected to have mastered at least one lightsaber form before becoming a Master, although this was not always the case, and most Masters studied a second form in addition to their first soon after achieving their rank.

It's generally considered that a period of ten-fifteen years is required to master a lightsaber form, although in some cases this may take exceedingly longer when a practitioner's natural temperament conflicts with their chosen form's styles and aesthetics.