We can have this fortune of touching the feet of Sri Mahaprabhuji if his grace is upon us. He accepts our seva when we render it with love and as a result your prostrating before him, you come out keeping your "apras", sit in a convenient place of sealusion and do japa and patha.
If you prefer to sit in front of Sri Mahaprabhuji to do japa-patha - keep your eyes open, concentrate your look on him, read sarvottam stotra without moving lips with interest and pure mind. Meditate on every word of the stotra glorifying and adding to the magnificience of Sri Mahaprabhuji - describing about his form and lilas. If we are unable to do this try to concentrate in the form of Sri Mahaprabhuji in your mind only and then recite Sri Sarvottam stotra silently. In a similar way you can do the japa or repeat the mala on Astakshara or Panch akshara Mantra.
If the Panch Akshara mantra is repeated in "apras" before Sri Mahaprabhuji or Sri Thakurji our "Ashreya" will become firm in the lotus like feet of divine being and develop "sarvottam Bhava" (i.e., tadiyatva sentiment). Hence you should repeat as many malas each of astakshara or Panchakshara as is possible. Side by side you should repeat one mala at least of Brahma Sambandha mantra. You can also read the works of Shodasgrantha of the time allows you to do in the circumstances.
As long as you stay in a Baithakji, forget about all materialistic avocations and keep yourself aloof from talking on worldly matters. You should decide to do this even before you leave your house spend most of your time on the "Smarana" of divine being.
If you are adapt in singing kirtans. You should sing kirtans sung at different times of the day and try to please Sri Mahaprabhuji. The kirtans sung in the presence of Sri Thakurji are part of seva. These songssung at proper time please Sri Thakurji. whereas songs sung during the period of "Anosar" are meant to remember the lila of divine being. So let us keep these important aspects in our mind while offering seva.
When you are in Baithakjies your time should be proportionately spent in seva an smarana.