In Sefer Daniel Perek 6' Posuk 11' when describing how Daniel, upon hearing the decree of the king not to pray to any other god accept for his, created an opening in his attic where he would be able to Daven with his eyes and heart towards Yerusholaim.
The reason being that our Tefilos are carried up to Shomaim via the Bais Ha'Mikdosh or even the Mokom Ha'Mikdash when its not standing such as in the times of Daniel himself. The window he created was a way to create a true longing for the Bais Ha'Mikdash as that would be equivalent to him being there as his heart is 'there'.
In the same vain, even when not davening in shul the Shulchon Aruch says in O.C. 90' 9' that one should make the effort and daven at the time the people are davening in shul which shall make your Tefilos get up there together with everybody else's as 'you' [at heart] are really 'there'.
The truth is that a person may be in shul and nevertheless be as if he were not there at all.It is for this reason that we say Ma Tovu when entering the shul in order to gain an appreciation for our Mikdash Me'at and thereby really be there.
Now, when davening at home one may also have his heart there and thereby really be there,in the shull or even in the BAIS HA'MIKDASH itself.
How? By saying Ma Tovu we shall truly have our hearts there and thereby really be there.
Remember the words Ma Tovu were originally said by someone really in the outside.The posuk Va'Ani berov chasdecha 'avow' baisecha is in future tense, meaning he is not there now.
In conclusion,the beautiful words of Ma Tovu is in essence not said when there,but rather 'it is which brings us there'.
See you there in the morning!!