Don't rush it, keep feeding it and when you get to the stage of making a loaf let it prove for much longer then usual. Overnight is good. It's a tasty loaf but takes two days in the making, once you have your starter. The first day the starter is out of the fridge, when at room temp feed it, 12 hours later start making the loaf, with a really long rise and prove and then bake.
Some starters have been kept going for years (50 and more), mine is only four years old and I have been months between loaves sometimes. It makes a really tasty loaf and is well worth the effort.