Compare pay down on mortgage now or in 4 months

I feel like my brain isn't working so looking for your input.

I have $600k left on mortgage which is up for renewal Jan 1, currently projecting a variable rate of 3.64%.

I plan to pay down $150k.

My bank (Meridian) just opened up a 4.7% promo for 4 months on new savings accounts.

I'm now comparing two scenarios:

1. I pay down $120k (20% allowed on current lender, easier than pay down between lenders), in late November. Then pay down the remaining $30k with the new lender.

or

2. I pay down $37k in late november, then when the promo is done pay down $113k (20% allowed).

In scenario 2 I make more money since the interest is higher than the mortgage rate, but this is all in taxable accounts as I don't have space in registered. This would be subject to 43.41% marginal tax. So is there an obvious choice or no just pick one and don't over think it?

Thanks