Mine took a year or too to get going. But the flowers are lovely when it does. David Austin roses, I find, need a bit more feeding and watering than others.
It's doing it all underground - developing a good root structure to support a lot of growth above - first things first
Mine took 2 years to get going, was hit bya hard winter and is now recovering and has done well this year. As Busy says, DA roses need a lot of feeding and watering to get underway but then they are glorious.
David Austin's roses take two to three years to fully establish in my experience, but once they get going look out they are wonderful. A shortcut is to buy the potted ones they do get going quicker.
I have lots of D Austin roses in ground and in pots. Falstaff is a really good one but be patient and feed well.