My advice considering you just started Ju Jutsu 4 months ago is first focus on real life responsibilities school or if your work full time of course, but as you continue your Ju-Jutsu spend any free time on studying Ju-Jutsu the theory and learn all the there is to know about the craft and study its form.
Apply those skills in practice and feel the movements and learn to flow with easy and make corrections, don't just jump into another art from just yet swallow one meal at a time.
You don't have go all the way in rank to master the form just take time to study it.
Links:-
Play with the idea of moving one way then countering another.
Also while you do this put into practice a good muscle and joint lessening stretching plan your are not going to master punching and kicking without first conditioning the body.
By the time you have done all this your body mechanics and flexibility would have the necessary preparation to move onto another martial art form like Kick Boxing or Tae Kwoon do, Muay Thai etc
So work on a "Martial Art Development Plan" first make actual notes:-
- Train on Ju-Jutsu
- Study on Ju-Jutsu
- The Movement
- The weak spots
- The frame work
- Formulate Tactics and Strategies in Defensive and Offensive from Ju-Jutsu
- Practice Ju-Jutsu
- Stretch upper muscles groups
- Stretch mid torso muscle groups
- Stretch leg muscle groups
- Learn about recovery and relaxation and breathing
- Do some light weight gym work on all areas of the body not muscle growth but strengthening
- Go running preferably on sand at beach or grass in a park area
That will keep you busy for a while and better prepare you in learning new forms and broadening your skill sets.
As an example some stretches to follow :-
There are heaps of online guides and tutorials or buy some books E.g. Comprehensive Body Conditioning - Stretching and Loosening Muscles study material
Are you planning on entering competition fights?
Its about mastering something first no need like I said to train 20 years in the one form when if you put more effort into it you can learn more through your own personal initiative.
Thats my advice and opinion in a nutshell!