If you are happy to rent for a year, you could put it on the market now and have a lot more flexibility in the purchase of your next property. You should check that you will get the mortgage for the upgrade, if required.
You say that selling prices in the area are varied, is it the selling prices or the 'asking prices' that are varied? Remember that not all people buying apartments are first time buyers, some people are trading down and a more mature development with nice views may appeal to them more.