(Firstly: not advice, secondly if you get hooked on options you
are going to lose everything eventually so never ever write options and don't buy them from margin, make sure your wife knows and approves of the worst-case loss beforehand or is of the forgiving type, etc., etc.)
So the problem with say the March 2019 calls is their huge implied volatility cost which comes mainly from their huge long-term time value - much of which time you'll spend waiting for no event you truly expect - i.e. between quarterly reports.
For example the $350 strike calls are $27 currently, so for a single contract you'd have to pay $2,700 cash, plus if you keep them until expiry the stock would have to hit at least $377 for it to be break-even.
So if your thesis is good
Q3 results, the timing should match that: i.e. be as close after the Nov 1-2 Q3 report as possible, i.e. Nov 02 expiry or Nov 16 expiry:
- Nov 02 is quite risky in that while the Q2 update letter was released on Aug 1, often Tesla delays their quarterly report to the 2nd or later day of the month and you might just miss it and the option expires without benefiting from any price action. This might explain why the total open interest is less than ~5,000 options and spreads are wide open.
- Nov 18 is much more crowded with 110K options and good liquidity, and say the $350 strike price trades at $10.
In terms of ideal strike level: depends on many things, but with a lottery ticket kind of jackpot-or-total-loss bet I'd go for max leverage without assuming a ridiculous price spike: say a mild short squeeze could spike to $400. With such a scenario and cashing out at $400 the $350-$370 strike levels look the most efficient at a quick glance.
If you want maximum leverage then you have to observe that option pricing drops sharply once the strike price goes outside the all time high: that's the historic range that current pricing assumes, and the price bounced from the ATH a couple of times so it is expected to be strong resistance.
But that 'bounces at $380-$390' is an argument based on technical analysis, if the breakthrough is fundamentals driven or short squeeze accelerated then that takes precedence over technical analysis and the price won't significantly bounce and you could trade on that hypothesis: in this case I'd go for a strike price around $440.
If you think the short squeeze is going to be unstoppable due to the magnitude of exposed short interest, i.e. the "milk Chanos to the max" lottery ticket, then I'd go for the highest strike price where you are not paying ridiculous spread to the market maker yet: for example $480 strike with a spread of ~20% looks acceptable, and the $0.50 price offers ridiculous leverage. These will most likely be lost though so buy them as if you bought really expensive ice cream or other luxury consumables. Write them off as a total loss mentally, the day you bought them.
You could also do a mix: if the first tier triggers you probably are in the green already in the end, with a nice profit. If the second tier triggers it's payday, if the third tier it's "set for life" day.
Note that if you think that either Q3 or Q4 results are going to be the day then it might still make sense to buy two expiries: the March 2019 $350 strike is trading at 2.7x the 2018/Nov $350 strike price. So if you first buy the Nov strike price, and then if it does not work out buy the March strike price (btw., April would be better), you are still only at a ~2x cost point instead of ~2x.
I.e. the best thing in the case of Tesla is to only pay the minimum time premium: which in this case would be to buy the options shortly before the delivery letter, and ride it through to shortly after the quarterly report. Note that at that point if the positive surprise happened as you expected it to, but you think the improved fundamentals have not yet fully been realized, or the short squeeze has not yet run to completion, you can still roll forward your calls week by week, with as much time value paid by your existing profits as you think is justified. (As long as you are certain that there won't be strong corrections, i.e. the fundamentals
truly improved and it's not a so-so quarter with some question marks.)
But I could be wrong about any of this - maybe others want to chime in?