Regarding 44ad and penalty for fy 2018-2019

You can pay it as Advance Tax even now and save yourself from paying interest under sec 234B.

However since default has been made, you are still liable to pay interest under sec 234C. 

For interest calculation, you can refer sec 234C of IT Act

Can you tell me when will 24f will be applicable on me.

I guess you mean Sec 234F and not sec 24F.

Sec 234F for filing returns of F.Y. 18-19, shall be applicable only if you fail to file returns before due date.

Ok so 234F considers a whole financial year and not the 15 March due date for advance tax? hope this is correct?

Thanks for clarification

One final question when will i be able to fill ITR for fy 2018-19