First don't expect it by 7/15 as the news is they may not start until August or later  and you should get a letter from the IRS if you are eligible for the advance credit along with the particulars on the situation. 

The increase in the child tax credit is effective for tax year 2021 to be filed next year, not for tax year 2020.

You may be eligible for an advance of the child tax credit to be paid during 2021.

See this IRS website for information - https://www.irs.gov/credits-deductions/advance-child-tax-credit-payments-in-2021

And this IRS website - https://www.irs.gov/newsroom/irs-sending-letters-to-more-than-36-million-families-who-may-qualify-fo...

The IRS will issue payments based on the number of qualifying child dependents you claimed on your 2020 tax return. The payments will go into the same bank account you used to receive your federal tax refund.  The advance payments will reduce the amount of child tax credit you would receive in your 2021 tax refund.

If you will be claiming fewer dependents on your 2021 tax return, you may want to unenroll from the advance payments because if you don't qualify when you file your tax return, the advance payments will have to be paid back.  If you used refund transfer, or you need to update your bank records for the deposits, you need to contact the IRS.  If you will be claiming a newborn child, you can update the IRS to receive payments. All these functions can be done at the IRS web site, although not all functions are turned on yet.

https://www.irs.gov/credits-deductions/advance-child-tax-credit-payments-in-2021