Should I max my HSA by the end of 2019? potential tax penalty...

[EricLThomp]

I just now got insurance for the first time this year on Oct 1. 
I contributed 1/12 of the max HSA contribution allowed for October. 
Should I do this again for Nov and again for Dec?
OR ---
I could pull out some savings and do the whole $3,500, but there's a pretty solid chance I could lose this job (and thus health-care) next year, and I read that there is a penalty if you don't pro-rate the contributions and don't have a HDHP the entire following year.  Can anyone shed light on this?
Thanks!

[MDM]

I could pull out some savings and do the whole $3,500, but there's a pretty solid chance I could lose this job (and thus health-care) next year, and I read that there is a penalty if you don't pro-rate the contributions and don't have a HDHP the entire following year.  Can anyone shed light on this?

Yes, per Publication 969 (2018), Health Savings Accounts and Other Tax-Favored Health Plans | Internal Revenue Service:
"If you fail to remain an eligible individual during the testing period, for reasons other than death or becoming disabled, you will have to include in income the total contributions made to your HSA that wouldn’t have been made except for the last-month rule. You include this amount in your income in the year in which you fail to be an eligible individual. This amount is also subject to a 10% additional tax. The income and additional tax are calculated on Form 8889, Part III."

[therethere]

If you think there is a decent chance you'll lose or change jobs I would just do the 3/12ths and call it a day. Because if you lost your job, the last thing you're going to want is more bills.

[Paul der Krake]

Note that if you lose your job towards the end of next year, you can always do COBRA long enough to avoid the penalty.

[dragoncar]

If you think there is a decent chance you'll lose or change jobs I would just do the 3/12ths and call it a day. Because if you lost your job, the last thing you're going to want is more bills.

Moreover, it would be nice to beef up the e-fund ahead of a likely job loss