In answer to the earlier questions -
Is there such a thing as too early for a chop? And will I need to have some of that sealing paste?
1. Yes there is such a thing as too early if you mean too early in the year. Maples can bleed badly when cut just before they bud up in spring but it is no problem when the leaves have opened like this. If your question refers to how old the tree needs to be then no, there is no such thing as too early. I sometimes cut really young seedlings at just a few months old if I want them to put out several low branches. The downside of cutting early is that it will slow growth a bit but if you set a good basis for future trunk shape it will probably be worth the tradeoff.
I would probably also shorten any side shoots you leave as well. You will have to do it later anyway, might as well do it all in one go.
With little trees like this I rarely use cut paste or any sealer. Sealing large cuts does help speed up healing but small cuts like this will heal over in no time anyway.