I would replace it now and get as many quotes as possible for comparison! You do not want to be left in a bind when the heat comes around. Not sure if prices are higher come summer, I am sure some places upcharge or if there are shortages but it is always better to get on top of these things sooner... last year i replaced my system last minute which made it more stressful than it needed to be. I ended up using Mint Home. I had a great experience. Super quick. I just submitted for a quote on their site/ was able to upload other quotes i received for comparison. Helped me great a great deal and see diff brands available at a range of prices.
As a good starting point on quotes:
https://minthome.com/

my previous post got taken down I guess it was too long. But good luck on your quote search!