Should I start doing other swar now ?

So i am doing sa in c3 pitch with tanpura for about 4 month now

I can now sing sa om and hmm in c pitch without tanpura

Can I now start with other swar ?

Which one to start with ? And how long time for one swar ?

I am a self learner

I have heard to start with pa in lower and higher octive

Like pa( lower ) sa( my natural pitch ) pa ( higher octive )

Then keep repeating this ?

And if I can do other swar can I just go directly to them or I have to do a warm up

What I usually do :- hmm ( 10 minutes) om ( 10 minutes ) sa 2-3 hours

If doing other swar than maybe 30min sa ?

Thanks