The browning of the oldest leaf tips is normal as your pineapple top gets going. Remember that it is a Bromeliad, and it doesn’t like to have sopping wet roots. That’s one reason pineapples do so well in Hawaii because the soil is volcanic and very porous. Your soil looks (hard to say from a photo) to be pretty heavy and moist. this could cause you a problem. If you think it is, unpot your plant and rinse the soil off the roots and just let it sit around somewhere for a few days, it won’t hurt it. Most bromeliads grow up in trees with no soil. And about a third or so of Perlite or pumice to your soil mix to open it up and make it more porous – replant your pineapple. I have grown them before and they actually grow quite fast and will get very large in no time once it takes off. To actually get fruit (which I did, albeit small but tasty!) it takes about two years and will eventually have to be growing in something like one of those half whiskey barrels – and it needs full sun all the time. I know that is going to be a trick where you live but you can winter it over inside and if nothing else it is a good conversation piece. Maybe it will take you longer than two years, I’m in southern California.