Is a long separation between the parts of al-muwālah (succession) stipulated not to occur, and does a long separation due to recalling the meanings of the testimony "There is no god but Allah" affect it?

There must be an order between the two testimonies when entering Islam: one must believe in Allah first, then in His Messenger. This opinion is more cautious. Some scholars, however, have stated that continuity between them is not a condition. So, if belief in the prophethood is delayed for a long period after belief in Allah the Almighty, it is still valid, and the separation between them, no matter how long, is not taken into consideration.