Shri Kavitaji,
First and foremost, when we are just referring to "Jai...!" and not saying it or writing the pavitra words directly to anybody our marg reet is that we write or say, 'Sadar Bhagvad Smaran' and not speak the words directly.
Like in: ' I met Rameshbhai in the morning and said 'Jai...!' to him" is wrong." I met Rameshbhai, and we said Bhagvad Smaran to each other" is correct.
Only when I am speaking to Rameshbhai directly should I say, "Rameshbhai, Jai..!"
Because the Jaikar of Prabhu is sarvottam, and there should always be an active response to it. Gramatically speaking, the actual words should never be spoken when speaking in the third person.
So, further I will refer to the words, " Jai..." as Bhagvad Smaran.
I always have an doubt that why we are not saying "Jai Shree Krishna" to Guruji
But when we say Bhagvad Smaran i.e. in simple words, you are reminding the other vaishnav of Shri Thakurji, and in turn he reminds you of Shri Thakurji. So that both vaishnavs, for a few moments, are transferred from a state of forgetfullness of Prabhu, to a state of smaran. That is the basic.
But the same vyavahar cannot be applied when in sanmukh of Shri Guruji. When we say it to Shri Vallabhkul, you are trying to remind Him of Shri Thakurji. It would be like asking your maths proffesor, ' Sir, do you remember 2 x 4 = 8 " Of course he remembers it, but our reminding him is not a compliment, but a mark of disrespect. The Guruji reminds us of Shri Thakurji, we don't need to remind them.
When we are in sanmukh of Shri Vallabhkul, we would like to receive their Ashirvads, so that through their Grace, WE always remember Shri Thakurji.that is foremost.
At that moment, reminding them of Shri Thakurji is not only a 'dosh' but we lose an oppurtunity to obtain Blessings. Some Vallabhukul out of their Deenta may say, "Jai Shri Krishna" in return, but we lost a golden avasar. So we say," Jai-Jai Dandvat ". So that they may Bless us. That is the correct prakar.
we always say "Jai Shree Krishna" to all Vaishnavs but not to Guruji.???
In our Sampradaya, there are three parts. Hari, Guru and Vaishnav. We give the same importance and respect to each of them. But our vyavahar with each is different. I mean we can't serve samagri to a Vaishnav first and then serve it to Shri Thakurji.
As there are only three parts, all Vaishnavs regardless of their age, caste etc are equal i.e. our vyavahar with every vaishnav should be same. So a young can do smaran to the old, the poor may do smaran to the rich etc. etc. So except for Shri Hari & Guru, smaran should be done to all Vaishnavs.
we are not saying "Jai Shree Krishna" in from of our God in Mandir
When we are sanmukh of Shri Thakurji or Shri Vallabhkul, they are our centre of attention, the only important relation at that time is that of a Swami, Sevak or Guru, Shishya. We chose to come to them, so all our other relations become unimportant then. Like talking on the mobile when doing shringar, i.e. disrespect. Or doing Bhagvad Smaran, or shaking hands, or bowing to other vaishnavs in sanmukh. By this we convey that our laukik relations are also important. And in sanmukh, when the swarup is there itself, what is the need of looking at each other and reminding them. Our only kriya at that time should be to have as much darshan or receive vachanmrat as possible.
However, We can do a Jai Ghosh. Shri Govardhannath ki Jai, Shri Vallabhadhish ki Jai...doing darshan of Shri Thakurji or Shri Vallabh, as that is not reminding anybody but a feeling of pride, a stuti, we should definitely do Jai-Kar.
Well, Sadar Bhagvad Smaran to all Vaishnavs,
PG