I would just shoot for the temp to start. Most of the conversion is done in the earlier part of the mash, so the temp is more important at the beginning, but just take good notes on temps and try to insulate the mash tun more if possible. I don't think a few degrees is a big deal, but its something I'd work on. I had a really crappy mash tun when I first started(very thin and lost temp pretty bad)-i bought an igloo ice cube and I don't lose a single degree the whole mash. Its great!