It depends on where you live. Each country has different meat diseases and bacterium that you have to be careful about
Traditionally in many western countries most meats are relatively safe raw though poultry is often not. But the definition of safe is not universal. Fresh chicken may have some salmonella etc, but unless this is allowed to grow to large numbers of spore it will not be dangerous. There are some bacteria that are dangerous in even minute amounts, but these should be vary rare, and even the cleanest cook will probably still transfer them
So to answer question, when cooking meat (or anything for that matter), you have to consider the amount of food adhering to the utensil, and the time it is exposed to a temperature in which bacteria can grow etc
If there was a formulae it would be something like
food type (risk of bacteria) * temperature * time
In general ground meat has been processed but not overly preserved, so time starts becoming a factor. How long has it been in a warm environment? Bacon is heavily preserved and not a great bacteria home, so you have more time before it becomes a risk. I small smear of bacon juice on a fork is not going to create a dangerous level of bacteria in the 20 minutes it takes you to cook the dish. But I wouldn't risk it for Chicken (in my country due to campylobacter still being a problem)
In the home environment I give anything that has touched raw food a quick rinse under the tap (Which just happens to be collected rain water and therefore full of bird poo :-) ) and sometimes a mechanical scrub with the dishes brush before using it again in the cooking process
There are lots of old wives tales on kitchen cleanliness, but the end result is that bacteria needs water, food, and temperature to grow. If you remove most of these they can't multiple to dangerous levels
From my experience in food technology laboratories, the often overlooked problem is surface oil and fat. These trap water, food and bacteria (the perfect storm). Simple mechanical scrubbing will remove vast amounts of these for short term (period of cooking) cleanliness
This of course does not apply to food that must be cooked for non bacterial reasons, and food known to be unclean. Chicken again is typical of this, and I would hot water scrub everything used with raw or partially cooked chicken
If you preheat the pan then you should be perfectly safe as the high heat should kill anything 'dangerous' before you add your meat for the second meal.
That said, I would point out that those oils left out are likely to begin to degrade immediately, causing your steak to take on some potentially undesirable FLAVORS.
Best Answer
The questions already asked are key: Will it be refrigerated and would you consider half cooked to be less safe than raw for a day?
To be safe, it would need to be promptly cooled to 40F or less and kept there. But, I would have another question for you to consider, is it fresh bacon, cured, cured and smoked or oven finished?
If cured and smoked, or oven finished, then it has already been treated in a preserving way and then cooked to typically 150 degrees, so this largely answers your question on if it is considered safe. It has already been done. If it is cured but not smoked, it likely has still been cooked, or half cooked if you will to the same temperature, just without smoke, but even if not logic would follow that it would be considered safe as long as you followed refrigeration standards and promptly. Fresh bacon though I would put in a complete different ballpark and I would be very hesitant to consider doing that, or even cured if it was slab rather than typical slices.
Now, the next question though is "Is it worth it?" What does it really gain you? If you properly cool half done bacon, now you have to reheat it from cold to serving temperature while finishing rendering the fat and cooking it the rest of the way without over cooking it. In my personal opinion, the end result is likely to be inferior quality though I like bacon less crispy and dried out than many people prefer. I would much prefer it cooked freshly, but as I make my own bacon I am pretty picky on what I consider good bacon. Note though that it really is not that uncommon, especially in fast food places and some breakfast diners, for bacon to be cooked ahead of time and then just reheated often in a microwave. I don't like it, but many are fine with it.
All that of course is assuming you are talking about typical US belly bacon. I would be very much against doing any of that with say a good back bacon, but it might still be safe. Just very low quality.