It's very rarely not a smart decision to make investments in Canada's Big 6, whether it be TD or any of the other 5.
They're trading at all time highs, but the environment looking forward is bullish. Some are overbought, and might be due for a bit of a correction or consolidation. But, the stocks I personally time my entries on the least is my blue-chip core holdings.
Obviously the future is never guaranteed, but if we look back to the last 25 years, if you have a long term mentality, there would be no situation where you'd be upset with purchasing Canadian bank stocks.