I remember reading a thread on gurmatbibek forum about this, I cant find it now but will post it if I do.
Some Singhs will say that a Sehaj Paath can only be classified as a Sehaj Paat if it is read from a saroop of Guru Sahib, and that if it is done by senchya/ online then it is not classified as a Sehaj Paat.
If you are able to do it from Mahraj's saroop then this would be ideal, however if this will be difficult then the next best solution may be to do it online or from senchya.
I did my first "Sehaj Paat" using the Gurbani Anywhere application for iPhones/iPods, as it allowed me to read translations at the same time.
Yes you should start with ardaas, and you can do it at any time of the day!
If what ive said is wrong, apologies...