You will invest new money by buying additional shares of your ETFs. How often you do it will depend on the terms of your online broker account.
Online broker investment accounts are insured through the Canadian Investor Protection Fund (check its members’ directory to make sure your provider is on the list).
If the ETFs in your portfolio declines in value, this insurance does not cover it. This is investment risk. Since you're holding a diversified fund, the loss may be caused by what happens in financial markets - you'll have to wait it out.
Similar to bank deposits GICs (up to 5 years) are insured by a government agency – the CDIC (Canada Deposit Insurance Corporation) or provincial equivalent, depending on the issuer.
Keep accumulating money in a your savings account (using a regular pre-authorized payment between your chequing and savings account).
Calculate the minimum transaction size in your online broker account, given commission you pay. Here's an example.
Whenever you reach this amount in your savings account, transfer it to your investment account and buy additional shares of your asset allocation ETF.
Make sure you're set up for money transfers between your chequing / savings account and online broker account.
Use the opportunity to rebalance your portfolio.
Key takeaways:
Most of the time rebalancing once a year is just fine, right after you looked at the investment performance of your portfolio.
It makes sense to time your rebalancing at the same time when you're making a large addition of new money to your account. It also makes sense to use ETF distributions / GIC interest in rebalancing.
But because index funds have no transaction fees, you can rebalance more often than once a year, when you're adding new money and especially if prices moved significantly and your asset mix is out of whack.
Monitor your account, but not too frequently. Once a year at least, every month may be too often. If you have GICs, you need to remember maturity dates - because you should reinvest the money as soon as the GIC matures. Always check the following:
How is your investment doing?
Price alone is not the best measure.
Total return measures how your investment has done over a period of time, usually a year.
You can use total return to compare your funds with other similar funds from different providers.
GICs are easy to monitor. The pay stated interest.
Your provider will most likely calculate the investment performance of your individual funds, but probably won't provide a measure of performance of your entire portfolio.
Check your ETF's tracking error. It should be small and not change much over time.
From time to time, you need to assess if your asset mix is still appropriate. Your risk appetite and investment horizon may have changed because something has changed in your life.
You don’t have to worry about income tax at all if this is a TFSA.
With other registered accounts, RESP and RRSP, you don't have to worry about income tax until you withdraw money.
You can invest new money as soon as you've saved enough to buy a few shares of your ETFs.
It makes sense to set up pre-authorized payments, likely from your chequing account, to regularly add new money to your investment.
If you have taxable accounts, you'll need to learn about investing and tax.