Stamp Duty Exempt?

[Ralphy01]

My husband has owned before we were married and appreciate that we will attract stamp duty in both names but understand that if bought in my name alone, I am legally exempt from stamp duty. I also understand that 'the buyer intends to live in the property and it will be their only or main home' (HMRC website), yet I have not seen any timescales attached to this caveat anywhere. Ultimately, the house will satisfy this, but for now, my husband is in the Armed Forces and, so we are not expecting to live in this house for another 5 yrs. Whether I choose to leave it empty or let my sister live in it (rent free) shouldn't affect this. In my eyes, I tick all the boxes to be classed as a first time buyer, it is just a question of timescale. I would be grateful for anyone's view on whether I qualify or not in this circumstance, and if so, does it make a difference if my husband then occupies the house with me (nothing found on this last point, anywhere). Many thanks.