COBRA can be enacted retroactively. You have 60 days to elect coverage, so you can wait until it's needed to enact it, but you will have to pay for the retro-active coverage. I did the same thing when I changed jobs last year and it saved me a ton rather than electing it right off the bat.

From www.cms.gov:

Qualified beneficiaries must notify the plan administer of their election according to the instructions laid out in the election notice. Qualified beneficiaries must be given an election period of at least 60 days during which each qualified beneficiary may choose whether to elect COBRA coverage. This period is measured from the later of the date of the qualifying event or the date the COBRA election notice is provided. COBRA coverage is retroactive if elected and paid for by the qualified beneficiary.

The ACA penalty only kicks in if it's been longer than 60 days, I believe. I'll try and find the specific wording about that. Definitely not something to worry about at this stage.

Here's a link to the healthcare.gov site relating to COBRA.

Does COBRA count as qualifying health coverage (or "minimum essential coverage")? Yes. This means if you have COBRA coverage you don’t have to pay the fee that people without coverage must pay.

COBRA can be enacted retroactively. You have 60 days to elect coverage, so you can wait until it's needed to enact it, but you will have to pay for the retro-active coverage. I did the same thing when I changed jobs last year and it saved me a ton rather than electing it right off the bat.

From www.cms.gov:

Qualified beneficiaries must notify the plan administer of their election according to the instructions laid out in the election notice. Qualified beneficiaries must be given an election period of at least 60 days during which each qualified beneficiary may choose whether to elect COBRA coverage. This period is measured from the later of the date of the qualifying event or the date the COBRA election notice is provided. COBRA coverage is retroactive if elected and paid for by the qualified beneficiary.

You can go up to 3 months before an ACA penalty might be assessed. I'll try and find the specific wording about that. Definitely not something to worry about at this stage.

Here's a link to the healthcare.gov site relating to COBRA.

Does COBRA count as qualifying health coverage (or "minimum essential coverage")? Yes. This means if you have COBRA coverage you don’t have to pay the fee that people without coverage must pay.

Update: Here's the IRS blurb about coverage gaps and ACA penalties:

22. What qualifies as a short coverage gap?

In general, a gap in coverage that lasts less than three months qualifies as a short coverage gap. If you have more than one short coverage gap during a year, the short coverage gap exemption only applies to the first gap.If you have a coverage gap of 3 months or more, you are not exempt for any of those months.