Planning to make a support wiz like this :
Wiz > Cry > Link > Thau > Chro > Chro/Alche
Nearly all the build I’ve seen go all the way to C2 Chrono for that ‘‘rollback’’ skill (which is an amazing skill btw), but I’m thorn between that and alchemist which seems quite nice too.
Any suggestions / advice ?
Well from what I see here, the only difference between c1 and c2 is that c2 has back masking and more proc on the skills but man the SP usage is so high on those levels beyond level 5 so you might want to consider that. Since you’re a support then there should be no issues with you going alchemist as your potions could really help any party at hand and at the same time, you can also earn money while you are sleeping 
Chrono 2 seems much more useful for a party, whereas Alchemist seems more useful for making money and items. Personally, out of those 2 builds, I would main Chrono2 and have an Alchemist as an alt to support that main.
Having said that, Alchemist has some really interesting skills and Magnus Opus recipes have not really been discovered yet. Since this is only a beta, if I was in your position I would choose Alchemist so I could play around with his skills and try to find some interesting Magnus recipes. There is nothing to lose, so on the last day of beta I would use ALL my items trying to find recipes. 
Alchemist is not going to be the 1st class I make, but if I can manage to get one before CBT ends I will certainly share my findings!
Glad to hear that XD
Also, once I’ve reached the end of the line on my main, I’m also gonna work on getting myself an alchemist as well in order to help on this complicated magnus opus