IIRC, about the same amount of time as you, maybe less. When I first got High Khatun, her first build gave her 228 SPD. What you really want to focus on is 3 speed sets, 5* or better, with double or better rolls on SPD, and throw in a few haste gliphs for good measure. This can get you to around 280, if you have a banner with double speed roll as well.

Speed sets you can get either from Dragon or from Campaign 6-6 and 6-7.

its all about luck.

you need rare/epic 5-6star pieces of speed set with speed substat and double/triple rolls on the speed substat plus 6 sar boots of speed set with speed mainstat and ideally with speed substat.

Just  to  clarify,  you  can't  get  a  speed  substat  on  boots  with  speed  main  stat.

But  take  6s  lego  boots  e.g.,  speed  main  stat  will  net  you  45  speed,  while  a  quad  roll  on  speed  substat  (very  difficult  to  get)  will  only  net  you  around  20-24  speed.

Yep, You can find SPD as a substat on all artifact gear, with the exception of Boots that have SPD as a main stat. In Addition, you can find additional SPD substats on your Banners, but not rings or amulets.

Speed tuning is deathly crucial for team optimization, and at the very least, having your champion's speeds curtailling your other champ's so that debuffs like DEF DOWN land before AoE attacks or INC ATK before AoE attacks.... obviously you probably know this by 60+ days in.

200+speed as a benchmark for all your champions may prove to be quite challenging for having just played 60 some odd days.. you will need 6 star fully ascended champs in order to see the highest base stats for them, and like I said Banners can offer more speed as well. This is not to say that you CANNOT reach 200 SPD without these things, however.

Id say if youve got your CB team down and are getting your highest chest, and can clear dragon 13 at the minimum you can start farming for speed gear. Some of my Champion's have 2 or even 3 full speed sets of gear on them, many of those pieces with double and triple rolls of SPD, and many of them without any SPD in the substats. Why? Because this is the easiest way to build speed for me, 12% to 24% to 36%, the latter almost giving as much SPD as a 5 star Speed boot artifact.

I consider myself to be in mid - to - midlate game, and 200 Speed as a threshold for my builds is very much attainable with a few of my champs hanging around 240-270 SPD. Even is the case for my tanks/HIGH RES/ and revivers.

There are champions that you can definitely get away without building much, if any speed at all for them, like a Vogoth. This is not recommended if you are putting any champion into a speed tuned CB comp though. There's an argument to be made, however, that Every champion should have a  certain minimum speed. ..It all comes down to what content and difficulty you are running, the speeds of the rest of your team, and is your fastest champ(s) fast enough to do their job effectively? If build too fast for a champion that overlaps another after [x] amount of turns, can throw off your team synergy and destroy the tune entirely. Watch out for TM Masteries, % chance to gain extra turn or reduce Cooldown Masteries, TM effects inside of abilities, (Special cases for Low ACC builds) & Abilities with an extra turn applied on themself - although this can be managed around with many of these types of champs.

In summation - Keep speed at the top of your mind when building, always - but do not forget about other stats... and if eventually you make an arena offense team with 4 level 60s that are fully maxxed, if going for highest possible speed, Only focus on SPD for your Champ(s) intended on taking the first turn i.e. your TM Booster/SPD Lead Aura Champ. Build rest of team around their %TM boost or the 30%INC SPD boost As well as their SPD, being careful not to fall beneath whatever -30% of said champ's base spd actually is, in respect to turn order -that way an enemy cannot cut inbetween any of your champs' turns.

 Ideally you want a 'One- hitter- Quitter' type of scenario. lol.