You shouldn't macro purple potions at least the targeting, you have a good chance of blowing off your fingers
Time and distance is relative to when you should throw it, but you can synch priming it with casting spells. I would use 5th circle or lower though, 6th circle pushes it too close especially when you include last target in your macro...it's better to target manually. Also if the guy comes right in on you when he sees your numbers ticking being he is in armor you might take the hit too and most likely worse. In casting 6th circle you got less then a second to freak and run
Seriously in my opinion fireball and potion (medieval cocktail) or even lightning is probably a better combo especially if you follow up with the hally and especially if they may have reflect items on and you are unsure if it will come back at you but still want to risk maybe causing some damage. If it does come back you got a little window in order to cast big if they do have MR items.
A dexxer doing this while changing from a two handed to one handed weapon or vice versa is better off, you would do this when you know your opponent is low on mana and want to get a big hit in or lay in to him. If your stamina is good you should be able to pull an instahit priming the potion in a macro that hits the potion inbetween changing weapons. Again you should manually target rather then depend on a macro to do so.
That is if nothing was changed in being able to throw pots with two handers. This would be the only time I would change weapons like that really at least concerning polearms because they are so slow. Yeah you can do big damage using them but for a mage instahit is better because they can precast, hit, then automatically go to small circle and do it again and it works because spells always hit. For a dexxer the best you can do is switch back to your faster weapon or try to instahit again and by that time the caster is already casting again. That's primarily what caused Mally to lose the fight in my opinion because he was experimenting with that. Yeah you might get lucky, but its a gamble.
Big weapons like that to me are better in group fights for dexxers when you can synch attacks or when using DP of course, then its a whole other ball game because you just bought time in them trying to cure. If you want to fight like a mage use potions and poisons to back it up....or 7th circle if you got the time, mana, and magery to do so (except in the case of the eval dexxer where you can cast anything and be effective).
You shouldn't do it often though poisons and potions aren't reliable enough to be effective all the time wait for the right opportunity to give it a shot such as right at the get go to put them on the defensive or when you know you are getting the upper hand and going in for the kill.
You notice a lot of dexxers avoid heavy armor because it drops their dex, and it's primarily because most have higher intelligence then 25 and strength at 100. Now I want you to realize something, you make up for lost hp in a higher ar especially if you include parry. Dropping Strength may at first sound like suicide if you think conventionally, but AR is in fact hps you always have each physical hit you endure that protect any hp you would lose otherwise.
Mally in his other thread said dex over 91 is overkill, well it is if you don't want to trade dex for more hit points. A female character in full plate armor from head to toe at 100 dex supped up on pots will have a max stamina of 105. Now you just added permanent hp in adding to your AR you wouldn't normally get even more if you had a shield. Now in realization of that you can lower both your strength and your dex to 95 and with a mage hat be able to cast 7th circle or in the case of being mind blasted to death boosted your intel without sacrificing your hp you picked up in parry and plate and still be able to swing fast even if your AR is through the roof. Yes, magery knows no AR, but when was the last time you were killed by a bard? The tank is dependent on his weaponry. (this is why I choose a studded gorget because with the mage hat my dex is at 91 so I can go in in full plate opening up with 7th circle and hally then immediately switching to broadsword and shield while I prep a bandage and don my helmet, change to plate gorget and eat something). Don't look at it like losing hit points think about it like gaining 2 hp in each area and in every swing that hits you compared to chainmail...not to mention what you get in parry. At 100 strength that number is boosted by 7 but then again you risk more damage from mindblast and it's impossible to cast 7th circle without sacrificing your swing speed. It's preference really.